Found 34 papers in cond-mat

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Exact Floquet flat band and heating suppression via two-rate drive protocols
Tista Banerjee, Sayan Choudhury, K. Sengupta
arXiv:2404.06536v1 Announce Type: new Abstract: We demonstrate the existence of exact Floquet flat bands implying strong violation of the eigenstate thermalization hypothesis in a large class of closed quantum many-body systems in the presence of a two-rate drive characterized by frequencies $\Omega_1$ and $\Omega_2=\nu \Omega_1$. We provide the exact analytic condition for this phenomenon to occur for a generic protocol; in particular, $\nu=(2p+1)$, where $p$ is an integer, leads to such flat bands for both square-pulse and cosine drive protocols for arbitrary $\Omega_1$. In the vicinity of these points, heating is suppressed up to very long timescales in such driven systems, leading to a prethermal regime; we demonstrate this by exact numerical studies of distribution and bandwidth of the Floquet eigenstates, spectral form factor, entanglement entropy, and correlation functions of an experimentally realizable finite driven Rydberg chain. The corresponding micromotion exhibits coherent reversal of excitation reminiscent of echoes. Our analysis constitutes a yet unexplored mechanism for heating suppression in driven closed quantum systems.

Robustness of topological magnons in disordered arrays of skyrmions
H. Diego Rosales, Roberto E. Troncoso
arXiv:2404.06541v1 Announce Type: new Abstract: The effects of disorder on the robustness of topological magnon states of two-dimensional ferromagnetic skyrmions is investigated. It is diagnosed by evaluating a real space topological invariant, the bosonic Bott index (BI). The disorder simultaneously breaks the axially symmetric shape and the crystalline ordering of the skyrmions array. The corresponding magnonic fluctuations and band spectrum are determined in terms of magnetic field and strength of disorder. We observe the closing of the existing band gaps as the individual skyrmions start to occupy random positions. The analysis reveals that topological states (TSs) persist beyond the perturbative limit when skyrmions reach the glassy phase. In addition, the localization of topologically protected edge states is weakened by the disordered skyrmion structure with increasing localization length. Our findings shed light on the physical understanding of the coexistence of disordered magnetic textures and their topological spin fluctuations.

Chiral two-dimensional MoS2 by molecular functionalization as ultra-sensitive detectors for circularly polarized light
Ye Wang, Yiru Zhu, Han Yan, Yang Li, Yan Wang, Manish Chhowalla
arXiv:2404.06555v1 Announce Type: new Abstract: Inducing chirality in optically and electronically active materials is interesting for applications in sensing and quantum information transmission. Two-dimensional (2D) transition metal chalcogenides (TMDs) possess excellent electronic and optical properties but are achiral. Here we demonstrate chirality induction in atomically thin layers of 2D MoS2 by functionalization with chiral thiol molecules. Analysis of X-ray absorption near-edge structure and Raman optical activity with circularly polarized excitation suggest chemical and electronic interactions that leads chirality transfer from the molecules to the MoS2. We confirm chirality induction in 2D MoS2 with circular dichroism measurements that show absorption bands at wavelengths of 380-520 nm and 520-600 nm with giant molar ellipticity of 10^8 deg cm2/dmol 2-3 orders of magnitude higher than 3D chiral materials. Phototransistors fabricated from atomically thin chiral MoS2 for detection of circularly polarized light exhibit responsivity of >10^2 A/W and maximum anisotropy g-factor of 1.98 close to the theoretical maximum of 2.0, which indicates that the chiral states of photons are fully distinguishable by the photodetectors. Our results demonstrate that it is possible achieve chirality induction in monolayer MoS2 by molecular functionalization and realise ultra-sensitive detectors for circularly polarized photons.

Subgap states in semiconductor-superconductor devices for quantum technologies: Andreev qubits and minimal Majorana chains
Rub\'en Seoane Souto, Ram\'on Aguado
arXiv:2404.06592v1 Announce Type: new Abstract: In recent years, experimental advances have made it possible to achieve an unprecedented degree of control over the properties of subgap bound states in hybrid nanoscale superconducting structures. This research has been driven by the promise of engineering subgap states for quantum applications, which includes Majorana zero modes predicted to appear at the interface of superconductor and other materials, like topological insulators or semiconductors. In this chapter, we revise the status of the field towards the engineering of quantum devices in controllable semiconductor-superconductor heterostructures. We begin the chapter with a brief introduction about subgap states, focusing on their mathematical formulation. After introducing topological superconductivity using the Kitaev model, we discuss the advances in the search for Majorana states over the last few years, highlighting the difficulties of unambiguously distinguish these states from nontopological subgap states. In recent years, the precise engineering of bound states by a bottom-up approach using quantum dots has led to unprecedented experimental advances, including experimental demonstrations of an Andreev qubits based on a quantum dot Josephson junction and a minimal Kitaev chain based on two quantum dots coherently coupled by the bound states of an intermediate superconducting segment. These experimental advances have revitalized the field and helped to understand that, far from being a disadvantage, the presence of subgap bound states can be exploited for new qubit designs and quantum coherence experiments, including Majorana-based qubits.

Noise-Tolerance of Majorana Teleportation in Mesoscopic Topological Superconductors
Tsukasa Goto, Masayuki Sugeta, Takeshi Mizushima, Satoshi Fujimoto
arXiv:2404.06677v1 Announce Type: new Abstract: We investigate teleportation interference associated with the non-local character of Majorana zero modes (MZMs) as a probe of MZMs focusing on the tolerance of teleportation against disturbances, such as inhomogeneous potentials at junctions and disorder. We develop a method for calculating non-local conductance in mesoscopic topological superconductors with fixed parity. In the trivial phase, the non-local conductance exhibits the $h/2e$-periodicity, while in the topological phase with fixed parity, it exhibits the $h/e$-periodicity, indicative of Majorana teleportation. We find that the $h/e$-periodicity is stable against changes in inhomogeneous potential structures and disorder. These results imply that MZMs can cause teleportation interference even in the presence of disturbances, leading to a clear distinction between the trivial and topological phases.

Many-defect solutions in planar nematics: interactions, spiral textures and boundary conditions
Simon \v{C}opar, \v{Z}iga Kos
arXiv:2404.06678v1 Announce Type: new Abstract: From incompressible flows to electrostatics, harmonic functions can provide solutions to many two-dimensional problems and, similarly, the director field of a planar nematic can be determined using complex analysis. We derive a closed-form solution for a quasi-steady state director field induced by an arbitrarily large set of point defects and circular inclusions with or without fixed rotational degrees of freedom, and compute the forces and torques acting on each defect or inclusion. We show that a complete solution must include two types of singularities, generating a defect winding number and its spiral texture, which have a direct effect on defect equilibrium textures and their dynamics. The solution accounts for discrete degeneracy of topologically distinct free energy minima which can be obtained by defect braiding. The derived formalism can be readily applied to equilibrium and slowly evolving nematic textures for active or passive fluids with multiple defects present within the orientational order.

Direct transition from a fractional quantum anomalous Hall state to a smectic state with the same Hall conductance
Hongyu Lu, Han-Qing Wu, Bin-Bin Chen, Zi Yang Meng
arXiv:2404.06745v1 Announce Type: new Abstract: The recent developments in twisted MoTe_2 and rhombohedral multilayer graphene have generated widespread attention to the general features of fractional quantum anomalous Hall (FQAH) states, including their possible coexistence with and transition to various symmetry breaking charge ordered states. These attentions are pushing forward our knowledge of the relation between the topological order in FQAH states and the Landau-type of symmetry breaking order such as the 1D smectic electronic liquid crystal and 2D charge-density-wave (CDW) solid. Although the transitions from topological states to symmetry breaking states with trivial topology have been discussed, the road from one topological ordered state to another with the same Hall conductance coexisting with Landau order has not been found. Here we show the intriguing evidence that the FQAH to FQAH Smectic (FQAHS) transition is robustly realizable in the archetypal correlated flat Chern-band model at filling {\nu} = 2/3. This transition is novel in that: i) the FQAHS acquires the same fractional Hall conductance as FQAH, which cannot be explained by mean-field band folding. The formation of smectic order can be viewed as perturbation around the transition point, and thus, do not destroy or change the original topology; ii) the charge excitation remains gapped across the transition although the neutral gap is closed at transition point; and iii) the transition is triggered by the softening of roton mode with the same wave vector as the smectic order. Our discovery opens countless new possibilities, both theoretical and experimental, in the fast-growing field of robust fractional Chern insulators.

Geometric frustration and Dzyaloshinskii-Moriya interactions in a quantum star lattice hybrid copper sulfate
Hajime Ishikawa, Yuto Ishii, Takeshi Yajima, Yasuhiro H. Matsuda, Koichi Kindo, Yusei Shimizu, Ioannis Rousochatzakis, Ulrich K. R\"o{\ss}ler, Oleg Janson
arXiv:2404.06783v1 Announce Type: new Abstract: We study the magnetism of a layered, spin-$\frac12$ organic-inorganic copper sulfate, which is a close realization of the star lattice antiferromagnet, one of the playgrounds of geometric frustration and resonating valence bond physics in two spatial dimensions. Our thermodynamic measurements show no ordering down to 0.1 K and a characteristic field-induced entropic shift, revealing the presence of an infinite number of competing states down to very low energy scales. The response to external magnetic fields shows, in addition, a peculiar anisotropy, reflected in the formation of a 1/3 magnetization plateau (stable up to full saturation around 105 T) and a paramagnetic, Curie-like susceptibility for one direction of the field (${\bf H}\parallel{\bf c}$), and a completely different response in other field directions. Our first-principles density functional theory calculations and exact diagonalizations show that these experimental puzzles are distinctive signatures of a strong interplay between geometric frustration and sizable Dzyaloshinskii-Moriya interactions, and the emergence of a continuous U(1) symmetry at low energy scales.

Control of proton transport and hydrogenation in double-gated graphene
J. Tong, Y. Fu, D. Domaretskiy, F. Della Pia, P. Dagar, L. Powell, D. Bahamon, S. Huang, B. Xin, R. N. Costa Filho, L. F. Vega, I. V. Grigorieva, F. M. Peeters, A. Michaelides, M. Lozada-Hidalgo
arXiv:2404.06823v1 Announce Type: new Abstract: Graphene's basal plane can function as a perfectly selective barrier permeable to protons but impermeable to all ions and gases, stimulating its use in applications such as membranes, catalysis and isotope separation. Protons can also chemically adsorb on graphene and hydrogenate it, inducing a conductor-insulator transition intensely explored in graphene electronic devices. However, both processes face energy barriers that in the case of proton transport motivate strategies to accelerate it, such as introducing vacancies, incorporating catalytic metals or chemically functionalising the lattice, but these can compromise other properties like ion selectivity or mechanical stability. Here we show that independent control of the electric field E~V nm-1 and charge carrier density n~10^14 cm-2 in double gated graphene allows decoupling proton transport from lattice hydrogenation and can accelerate proton transport such that it approaches the limiting electrolyte current in our devices. Proton transport and hydrogenation can be driven selectively with precision and robustness that enables proton-based logic-and-memory graphene devices with orders-of-magnitude on-off ratios. Our results show that field effects can accelerate and decouple electrochemical processes in double-gated 2D crystals and demonstrate the possibility of mapping such processes as a function of E and n - a fundamentally different technique to study 2D electrode-electrolyte interfaces.

Topological states constructed by two different trivial quantum wires
Jing-Run Lin, Linxi Lv, Zheng-Wei Zuo
arXiv:2404.06886v1 Announce Type: new Abstract: The topological states of the two-leg and three-leg ladders formed by two trivial quantum wires with different lattice constants are theoretically investigated. For the symmetric nearest-neighbor intra-chain hopping two-leg ladder, the inversion symmetry topological insulator phase with two degenerate topological edge states appears. When the inversion symmetry is broken, the topological insulators with one or two topological edge states of different energies and topological metals with edge states embedded in the bulk states could emerge dependent on the filling factor. The topological origin of these topological states in the two-leg ladders is the topological properties of the Chern insulators and Chern metals. According to the arrangement of two trivial quantum wires, we construct two types of three-leg ladders. Each type of the three-leg ladder could be divided into one trivial subspace and one topological nontrivial subspace by unitary transformation. The topological nontrivial subspace corresponds to the effective two-leg ladder model. As the filling factor changes, the system could be in topological insulators or topological metals phases. These rich topological states in the two-leg and three-leg ladders could be confirmed by current experimental techniques.

Unravelling the Band Structure and Orbital Character of a $\pi$-Conjugated 2D Graphdiyne-Based Organometallic Network
Paolo D'Agosta (Politecnico di Milano, Italy), Simona Achilli (Universit\`a degli Studi di Milano, Italy), Francesco Tumino (Politecnico di Milano, Italy, Queen's University, Kingston, Canada), Alessio Orbelli Biroli (Universit\`a di Pavia, Italy), Giovanni Di Santo (Elettra Sincrotrone Trieste, Italy), Luca Petaccia (Elettra Sincrotrone Trieste, Italy), Giovanni Onida (Universit\`a degli Studi di Milano, Italy), Andrea Li Bassi (Politecnico di Milano, Italy), Jorge Lobo-Checa (Instituto de Nanociencia y Materiales de Arag\'on, Zaragoza, Spain, Universidad de Zaragoza, Spain), Carlo S. Casari (Politecnico di Milano, Italy)
arXiv:2404.06896v1 Announce Type: new Abstract: Graphdiyne-based carbon systems generate intriguing layered sp-sp$^2$ organometallic lattices, characterized by flexible acetylenic groups connecting planar carbon units through metal centers. At their thinnest limit, they can result in two-dimensional (2D) organometallic networks exhibiting unique quantum properties and even confining the surface states of the substrate, which is of great importance for fundamental studies. In this work, we present the on-surface synthesis of a highly crystalline 2D organometallic network grown on Ag(111). The electronic structure of this mixed honeycomb-kagome arrangement - investigated by angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy - reveals a strong electronic conjugation within the network, leading to the formation of two intense electronic band-manifolds. In comparison to theoretical density functional theory calculations, we observe that these bands exhibit a well-defined orbital character that can be associated with distinct regions of the sp-sp$^2$ monomers. Moreover, we find that the halogen by-products resulting from the network formation locally affect the pore-confined states, causing a significant energy shift. This work contributes to the understanding of the growth and electronic structure of graphdiyne-like 2D networks, providing insights into the development of novel carbon materials beyond graphene with tailored properties.

The effects of V doping on the intrinsic properties of SmFe10Co2 alloys: a theoretical investigation
Diana Benea, Viorel Pop, Jan Min\'ar
arXiv:2404.06897v1 Announce Type: new Abstract: The present study focuses on the intrinsic properties of the SmFe10Co2-xVx (x = 0-2) alloys, which includes the SmFe10Co2 alloy, one of the most promising permanent magnets with the ThMn12 type of structure due to its large saturation magnetization (1.78 T), high Curie temperature (Tc = 859 K), and anisotropy field (12 T) experimentally obtained. Unfortunately, its low coercivity (<0.4 T) hinders its use in permanent magnet applications. The effect of V-doping on magnetization, magnetocrystalline anisotropy energy, and Curie temperature is investigated by electronic band structure calculations. The spin-polarized fully relativistic Korringa-Kohn-Rostoker (SPR-KKR) band structure method, which employs the coherent potential approximation (CPA) to deal with substitutional disorder, has been used. The Hubbard-U correction to local spin density approximation (LSDA +U) was used to account for the large correlation effects due to the 4f electronic states of Sm. The computed magnetic moments and magnetocrystalline anisotropy energies were compared with existing experimental data to validate the theoretical approach's reliability. The exchange-coupling parameters from the Heisenberg model were used for obtaining the mean-field estimated Curie temperature. The magnetic anisotropy energy was separated into contributions from transition metals and Sm, and its relationships with the local environment, interatomic distances, and valence electron delocalization were analyzed. The suitability of the hypothetical SmFe10CoV alloy for permanent magnet manufacture was assessed using the calculated anisotropy field, magnetic hardness, and intrinsic magnetic properties.

SQUID oscillations in PbTe nanowire networks
Yichun Gao, Wenyu Song, Zehao Yu, Shuai Yang, Yuhao Wang, Ruidong Li, Fangting Chen, Zuhan Geng, Lining Yang, Jiaye Xu, Zhaoyu Wang, Zonglin Li, Shan Zhang, Xiao Feng, Tiantian Wang, Yunyi Zang, Lin Li, Runan Shang, Qi-Kun Xue, Ke He, Hao Zhang
arXiv:2404.06899v1 Announce Type: new Abstract: Network structures by semiconductor nanowires hold great promise for advanced quantum devices, especially for applications in topological quantum computing. In this study, we created networks of PbTe nanowires arranged in loop configurations. Using shadow-wall epitaxy, we defined superconducting quantum interference devices (SQUIDs) using the superconductor Pb. These SQUIDs exhibit oscillations in supercurrent upon the scanning of a magnetic field. Most of the oscillations can be fitted assuming a sinusoidal current-phase relation for each Josephson junction. Under certain conditions, the oscillations are found to be skewed, suggesting possible deviation from a sinusoidal behavior. Our results highlight the potential of PbTe nanowires for building complex quantum devices in the form of networks.

Multifractal phase in the weighted adjacency matrices of random Erd\"os-R\'enyi graphs
Leticia F. Cugliandolo, Gr\'egory Schehr, Marco Tarzia, Davide Venturelli
arXiv:2404.06931v1 Announce Type: new Abstract: We study the spectral properties of the adjacency matrix in the giant connected component of Erd\"os-R\'enyi random graphs, with average connectivity $p$ and randomly distributed hopping amplitudes. By solving the self-consistent cavity equations satisfied by the matrix elements of the resolvent, we compute the probability distribution of the local density of states, which governs the scaling with the system size of the moments of the eigenvectors' amplitudes, as well as several other observables related to the spectral statistics. For small values of $p>1$ above the percolation threshold, we unveil the presence of an exotic delocalized but (weakly) multifractal phase in a broad region of the parameter space, which separates the localized phase found for $p\le1$ from the fully-delocalized GOE-like phase expected for $p\to \infty$. We explore the fundamental physical mechanism underlying the emergence of delocalized multifractal states, rooted in the pronounced heterogeneity in the topology of the graph. This heterogeneity arises from the interplay between strong fluctuations in local degrees and hopping amplitudes, and leads to an effective fragmentation of the graph. We further support our findings by characterizing the level statistics and the two-point spatial correlations within the multifractal phase, and address the ensuing anomalous transport and relaxation properties affecting the quantum dynamical evolution.

Optimal Matching of Thermal Vibrations into Carbon Nanotubes
K. G. S. H. Gunawardana, Kieran Mullen
arXiv:2404.06938v1 Announce Type: new Abstract: Carbon nanotubes (CNTs) are promising candidates to improve the thermal conductivity of nano-composites. The main obstacle to these applications is the extremely high thermal boundary (Kapitza) resistance between the CNTs and their matrix. In this theoretical work our goal is to maximize the heat flux through the CNT by functionalizing the CNT ends. We use a Landauer approach to calculate and optimize the energy flux from a soft to a hard material in one dimension through a connecting continuous medium of varying elasticity and density. The transmission probability of phonons through the system is calculated both numerically and analytically. We find that over 90% of the maximum heat flux into CNT is possible for 1nm length of the intermediate material at room temperature (300K).

Three-dimensional ${\mathbb Z}_2$-gauge $N$-vector models
Claudio Bonati, Andrea Pelissetto, Ettore Vicari
arXiv:2404.07050v1 Announce Type: new Abstract: We study the phase diagram and critical behaviors of three-dimensional lattice ${\mathbb Z}_2$-gauge $N$-vector models, in which an $N$-component real field is minimally coupled with a ${\mathbb Z}_2$-gauge link variables. These models are invariant under global O($N$) and local ${\mathbb Z}_2$ transformations. They present three phases characterized by the spontaneous breaking of the global O($N$) symmetry and by the different topological properties of the ${\mathbb Z}_2$-gauge correlations. We address the nature of the three transition lines separating the three phases. The theoretical predictions are supported by numerical finite-size scaling analyses of Monte Carlo data for the $N=2$ model. In this case, continuous transitions can be observed along both transition lines where the spins order, in the regime of small and large inverse gauge coupling $K$. Even though these continuous transitions belong to the same $XY$ universality class, their critical modes turn out to be different. When the gauge variables are disordered (small $K$), the relevant order-parameter field is a gauge-invariant bilinear combination of the vector field. On the other hand, when the gauge variables are ordered (large $K$), the order-parameter field is the gauge-dependent $N$-vector field, whose critical behavior can only be probed by using a stochastic gauge fixing that reduces the gauge freedom.

Multiscale structure-property discovery via active learning in scanning tunneling microscopy
Ganesh Narasimha, Dejia Kong, Paras Regmi, Rongying Jin, Zheng Gai, Rama Vasudevan, Maxim Ziatdinov
arXiv:2404.07074v1 Announce Type: new Abstract: Atomic arrangements and local sub-structures fundamentally influence emergent material functionalities. The local structures are conventionally probed using spatially resolved studies and the property correlations are usually deciphered by a researcher based on sequential explorations and auxiliary information, thus limiting the throughput efficiency. Here we demonstrate a Bayesian deep learning based framework that automatically correlates material structure with its electronic properties using scanning tunneling microscopy (STM) measurements in real-time. Its predictions are used to autonomously direct exploration toward regions of the sample that optimize a given material property. This autonomous method is deployed on the low-temperature ultra-high vacuum STM to understand the structure-property relationship in a europium-based semimetal, EuZn2As2, one of the promising candidates for studying the magnetism-driven topological properties. The framework employs a sparse sampling approach to efficiently construct the scalar-property space using a minimal number of measurements, about 1 - 10 % of the data required in standard hyperspectral imaging methods. We further demonstrate a target-property-guided active learning of structures within a multiscale framework. This is implemented across length scales in a hierarchical fashion for the autonomous discovery of structural origins for an observed material property. This framework offers the choice to select and derive a suitable scalar property from the spectroscopic data to steer exploration across the sample space. Our findings reveal correlations of the electronic properties unique to surface terminations, local defect density, and point defects.

Probing phase transitions with correlations in configuration space: a Monte Carlo study on lattice models
Wen-Yu Su, Yu-Jing Liu, Nvsen Ma, Chen Cheng
arXiv:2404.07087v1 Announce Type: new Abstract: While phases and phase transitions are mostly characterized by order parameters or physical quantities in real space, we propose that the correlation in Hilbert space is closely connected to phase transitions. Specifically, this correlation is quantified by the 1-norm distance between configurations, and the distribution of distances can be obtained from a small fraction of configurations in the exponentially large Hilbert space, with the help of importance sampling procedures of the Monte Carlo method. Considering the obtained distances as a data set, its distribution varies substantially in different phases, and the numerical results further suggest a universal critical behavior for the uncertainty and participation entropy extracted from it. For various classical spin models with different types of phases and phase transitions, the finite-size analysis based on these quantities successfully catches the phase transitions with accurate critical points. Moreover, in all cases for different systems and phase transitions, the critical exponent from the uncertainty of the distances is found to numerically equal the anomalous dimension that determines the decay of the correlation in real space. This implies a deeper connection between the correlation in the real space and configuration space, which deserves further investigation. In our proposal, the definition of distance covers various lattice models with different local degrees of freedom, e.g., two levels for Ising-like models, discrete multi-levels for $q$-state clock models, and continuous local levels for the $XY$ model, and the way handling the distances is very simple and robust. Our proposal provides an alternative way of understanding the complex phases and phase transitions in complicated systems where the order parameter is hard to compute or define.

Local probe of bulk and edge states in a fractional Chern insulator
Zhurun Ji, Heonjoon Park, Mark E. Barber, Chaowei Hu, Kenji Watanabe, Takashi Taniguchi, Jiun-Haw Chu, Xiaodong Xu, Zhi-xun Shen
arXiv:2404.07157v1 Announce Type: new Abstract: Fractional quantum Hall effect (FQHE) is a prime example of topological quantum many-body phenomena, arising from the interplay between strong electron correlation, topological order, and time reversal symmetry breaking. Recently, a lattice analog of FQHE at zero magnetic field has been observed, confirming the existence of a zero-field fractional Chern insulator (FCI). Despite this, the bulk-edge correspondence -- a hallmark of FCI featuring an insulating bulk with conductive edges -- has not been directly observed. In fact, this correspondence has not been visualized in any system for fractional states due to experimental challenges. Here we report the imaging of FCI edge states in twisted MoTe2 by employing a newly developed modality of microwave-impedance microscopy. By tuning the carrier density, we observe the system evolving between metallic and FCI states, the latter of which exhibits insulating bulk and conductive edges as expected from bulk-boundary correspondence. We also observe the evolution of edge states across the topological phase transition from an incompressible Chern insulator state to a metal and finally to a putative charge ordered insulating state as a function of interlayer electric field. The local measurement further reveals tantalizing prospects of neighboring domains with different fractional orders. These findings pave the way for research into topologically protected 1D interfaces between various anyonic states at zero magnetic field, such as topological entanglement entropy, Halperin-Laughlin interfaces, and the creation of non-abelian anyons.

Pressure-tuned many-body phases through $\Gamma$-K valleytronics in moir\'e bilayer WSe$_2$
Marta Brzezi\'nska, Sergii Grytsiuk, Malte R\"osner, Marco Gibertini, Louk Rademaker
arXiv:2404.07165v1 Announce Type: new Abstract: Recent experiments in twisted bilayer transition-metal dichalcogenides have revealed a variety of strongly correlated phenomena. To theoretically explore their origin, we combine here ab initio calculations with correlated model approaches to describe and study many-body effects in twisted bilayer WSe$_2$ under pressure. We find that the interlayer distance is a key factor for the electronic structure, as it tunes the relative energetic positions between the K and the $\Gamma$ valleys of the valence band maximum of the untwisted bilayer. As a result, applying uniaxial pressure to a twisted bilayer induces a charge-transfer from the K valley to the flat bands in the $\Gamma$ valley. Upon Wannierizing moir\'e bands from both valleys, we establish the relevant tight-binding model parameters and calculate the effective interaction strengths using the constrained random phase approximation. With this, we approximate the interacting pressure-doping phase diagram of WSe$_2$ moir\'e bilayers using self-consistent mean field theory. Our results establish twisted bilayer WSe$_2$ as a platform that allows the direct pressure-tuning of different correlated phases, ranging from Mott insulators, charge-valley-transfer insulators to Kondo lattice-like systems.

Laser driven melt pool resonances through dynamically oscillating energy inputs
Marco Rupp, Karen Schwarzkopf, Markus Doering, Shuichiro Hayashi, Michael Schmidt, Craig B. Arnold
arXiv:2404.07195v1 Announce Type: new Abstract: Spatially selective melting of metal materials by laser irradiation allows for the precise welding as well as the 3D printing of complex metal parts. However, the simple scanning of a conventional Gaussian beam typically results in a melt track with randomly distributed surface features due to the complex and dynamic behavior of the melt pool. In this study, the implications of utilizing a dynamically oscillating energy input on driving melt track fluctuations is investigated. Specifically, the laser intensity and/or intensity distribution is sinusoidally modulated at different scan speeds, and the effect of modulation frequency on the resulting surface features of the melt track is examined. The formation of periodically oriented surface features indicates an evident frequency coupling between the melt pool and the modulation frequency. Moreover, such a frequency coupling becomes most prominent under a specific modulation frequency, suggesting resonant behavior. The insights provided in this study will enable the development of novel methods, allowing for the control and/or mitigation of inherent fluctuations in the melt pool through laser-driven resonances.

Statistical evaluation of 571 GaAs quantum point contact transistors showing the 0.7 anomaly in quantized conductance using millikelvin cryogenic on-chip multiplexing
Pengcheng Ma, Kaveh Delfanazari, Reuben K. Puddy, Jiahui Li, Moda Cao, Teng Yi, Jonathan P. Griffiths, Harvey E. Beere, David A. Ritchie, Michael J. Kelly, Charles G. Smith
arXiv:2404.06784v1 Announce Type: cross Abstract: The mass production and the practical number of cryogenic quantum devices producible in a single chip are limited to the number of electrical contact pads and wiring of the cryostat or dilution refrigerator. It is, therefore, beneficial to contrast the measurements of hundreds of devices fabricated in a single chip in one cooldown process to promote the scalability, integrability, reliability, and reproducibility of quantum devices and to save evaluation time, cost and energy. Here, we use a cryogenic on-chip multiplexer architecture and investigate the statistics of the 0.7 anomaly observed on the first three plateaus of the quantized conductance of semiconductor quantum point contact (QPC) transistors. Our single chips contain 256 split gate field effect QPC transistors (QFET) each, with two 16-branch multiplexed source-drain and gate pads, allowing individual transistors to be selected, addressed and controlled through an electrostatic gate voltage process. A total of 1280 quantum transistors with nano-scale dimensions are patterned in 5 different chips of GaAs heterostructures. From the measurements of 571 functioning QPCs taken at temperatures T= 1.4 K and T= 40 mK, it is found that the spontaneous polarisation model and Kondo effect do not fit our results. Furthermore, some of the features in our data largely agreed with van Hove model with short-range interactions. Our approach provides further insight into the quantum mechanical properties and microscopic origin of the 0.7 anomaly in QPCs, paving the way for the development of semiconducting quantum circuits and integrated cryogenic electronics, for scalable quantum logic control, readout, synthesis, and processing applications.

Ubiquitous light real-space pairing from long-range hopping and interactions
G. D. Adebanjo, J. P. Hague, P. E. Kornilovitch
arXiv:2211.06498v3 Announce Type: replace Abstract: We systematically examine how long-range hopping and its synergy with extended interactions leads to light bound pairs. Pair properties are determined for a dilute extended Hubbard model with large on-site repulsion ($U$) and both near- and next-nearest neighbour hopping ($t$ and $t'$) and attraction ($V$ and $V'$), for cubic and tetragonal lattices. The presence of $t'$ and $V'$ promotes light pairs. For tetragonal lattices, $t'<0$ pairs can be lighter than non-interacting particles, and $d$-symmetric pairs form. Close packing transition temperatures, $T^{\ast}$ are estimated for the Bose-Einstein condensation (BEC) of pairs to be $k_{B}T^{\ast}\sim\overline{t} 0.1$, where $\overline{t}$ is the geometric mean of the hoppings on the Cartesian axes. When pairs have $d$-symmetry, the condensate has $d$-wave character. Thus, the presence of both $t'$ and $V'$ leads ubiquitously to small strongly bound pairs with an inverse mass that is linear in hopping, which could lead to high temperature BECs.

Pauli blockade catalogue and three- and four-particle Kondo effect in bilayer graphene quantum dots
Chuyao Tong, Annika Kurzmann, Rebekka Garreis, Kenji Watanabe, Takashi Taniguchi, Thomas Ihn, Klaus Ensslin
arXiv:2305.03479v2 Announce Type: replace Abstract: Pauli blockade is a fundamental quantum phenomenon that also serves as a powerful tool for qubit manipulation and read-out. While most systems exhibit a simple even-odd pattern of double-dot Pauli spin blockade due to the preferred singlet pairing of spins, the additional valley degree of freedom offered by bilayer graphene greatly alters this pattern. Inspecting bias-triangle measurements at double-dot charge degeneracies with up to four electrons in each dot reveals a much richer double-dot Pauli blockade catalogue with both spin and/or valley blockade. In addition, we use single-dot Kondo effect measurements to substantiate our understanding of the three- and four-particle state spectra by analyzing their magnetic field dependence. With high controllability and reported long valley- and spin-relaxation times, bilayer graphene is a rising platform for hosting semiconductor quantum dot qubits. A thorough understanding of state spectra is crucial for qubit design and manipulation, and the rich Pauli blockade catalogue provides an abundance of novel qubit operational possibilities and opportunities to explore intriguing spin and valley physics.

Finite-Size Scaling of the High-Dimensional Ising Model in the Loop Representation
Tianning Xiao, Zhiyi Li, Zongzheng Zhou, Sheng Fang, Youjin Deng
arXiv:2310.11712v3 Announce Type: replace Abstract: Besides its original spin representation, the Ising model is known to have the Fortuin-Kasteleyn (FK) bond and loop representations, of which the former was recently shown to exhibit two upper critical dimensions $(d_c=4,d_p=6)$. Using a lifted worm algorithm, we determine the critical coupling as $K_c = 0.077\,708\,91(4)$ for $d=7$, which significantly improves over the previous results, and then study critical geometric properties of the loop-Ising clusters on tori for spatial dimensions $d=5$ to 7. We show that, as the spin representation, the loop Ising model has only one upper critical dimension at $d_c=4$. However, sophisticated finite-size scaling (FSS) behaviors, like two length scales, two configuration sectors and two scaling windows, still exist as the interplay effect of the Gaussian fixed point and complete-graph asymptotics. Moreover, using the Loop-Cluster algorithm, we provide an intuitive understanding of the emergence of the percolation-like upper critical dimension $d_p=6$ in the FK-Ising model. As a consequence, a unified physical picture is established for the FSS behaviors in all the three representations of the Ising model above $d_c=4$.

Demonstration of tritium adsorption on graphene
Genrich Zeller, Desedea Diaz Barrero, Paul Wiesen, Simon Niemes, Nancy Tuchscherer, Max Aker, Artus M. W. Leonhardt, Jannik Demand, Kathrin Valerius, Beate Bornschein, Magnus Schl\"osser, Helmut H. Telle
arXiv:2310.16645v2 Announce Type: replace Abstract: In this work, we report on studies of graphene exposed to tritium gas in a controlled environment. The single layer graphene on a $\textrm{SiO}_2$/Si substrate was exposed to 400 mbar of $\textrm{T}_2$ for a total time of $\approx$ 55 h. The resistivity of the graphene sample was measured $\textit{in situ}$ during tritium exposure using the Van der Pauw method. We found that the sheet resistance increases by three orders of magnitude during the exposure, suggesting significant chemisorption of tritium. After exposure, the samples were characterised $\textit{ex situ}$ via spatio-chemical mapping with a confocal Raman microscope, to study the effect of tritium on the graphene structure (tritiation yielding T-graphene), as well as the homogeneity of modifications across the whole area of the graphene film. The Raman spectra after tritium exposure were comparable to previously observed results in hydrogen-loading experiments, carried out by other groups. By thermal annealing we also could demonstrate, using Raman spectral analysis, that the structural changes were largely reversible. Considering all observations, we conclude that the graphene film was at least partially tritiated during the tritium exposure, and that the graphene film by and large withstands the bombardment by electrons from the $\beta$-decay of tritium, as well as by energetic primary and secondary ions.

Ordering Kinetics of the two-dimensional voter model with long-range interactions
Federico Corberi, Luca Smaldone
arXiv:2312.00743v2 Announce Type: replace Abstract: We study analytically the ordering kinetics of the two-dimensional long-range voter model on a two-dimensional lattice, where agents on each vertex take the opinion of others at distance $r$ with probability $P(r) \propto r^{-\al}$. The model is characterized by different regimes, as $\al$ is varied. For $\al > 4$ the behaviour is similar to that of the nearest-neighbor model, with the formation of ordered domains of a typical size growing as $L(t) \propto \sqrt{t}$, until consensus is reached in a time or order $N\ln N$, $N$ being the number of agents. Dynamical scaling is violated due to an excess of interfacial sites whose density decays as slow as $\rho(t) \propto 1/\ln t$. Sizable finite-time corrections are also present, which are absent in the case of nearest-neighbors interactions. For $0<\al \leq 4$ standard scaling is reinstated, and the correlation length increases algebraically as $L(t)\propto t^{1/z}$, with $1/z=2/\al$ for $3<\al<4$ and $1/z=2/3$ for $0<\al<3$. In addition, for $\al \le 3$, $L(t)$ depends on $N$ at any time $t>0$. Such coarsening, however, only leads the system to a partially ordered metastable state where correlations decay algebraically with distance, and whose lifetime diverges in the $N\to \infty$ limit. In finite systems consensus is reached in a time of order $N$ for any $\al <4$.

Thermal conductivity of macroporous graphene aerogel measured using high resolution comparative infrared thermal microscopy
Jasmine M. Cox, Jessica J. Frick, Chen Liu, Zhou Li, Yaprak Ozbakir, Carlo Carraro, Roya Maboudian, Debbie G. Senesky
arXiv:2305.09033v3 Announce Type: replace-cross Abstract: Graphene aerogel (GA) is a promising material for thermal management applications across many fields due to its lightweight and thermally insulative properties. However, standard values for important thermal properties, such as thermal conductivity, remain elusive due to the lack of reliable characterization techniques for highly porous materials. Comparative infrared thermal microscopy (CITM) is an attractive technique to obtain thermal conductance values of porous materials like GA, due to its non-invasive character, which requires no probing of, or contact with, the often-delicate structures and frameworks. In this study, we improve upon CITM by utilizing a higher resolution imaging setup and reducing the need for pore-filling coating of the sample (previously used to adjust for emissivity). This upgraded setup, verified by characterizing porous silica aerogel, allows for a more accurate confirmation of the fundamental thermal conductivity value of GA while still accounting for the thermal resistance at material boundaries. Using this improved method, we measure a thermal conductivity below 0.036 W/m$\cdot$K for commercial GA using multiple reference materials. These measurements demonstrate the impact of higher resolution thermal imaging to improve accuracy in low density, highly porous materials characterization. This study also reports thermal conductivity for much lower density (less than 15 mg/cm$^3$) GA than previously published studies while maintaining the robustness of the CITM technique.

Separability transitions in topological states induced by local decoherence
Yu-Hsueh Chen, Tarun Grover
arXiv:2309.11879v2 Announce Type: replace-cross Abstract: We study states with intrinsic topological order subjected to local decoherence from the perspective of separability, i.e., whether a decohered mixed state can be expressed as an ensemble of short-range entangled (SRE) pure states. We focus on toric codes and the X-cube fracton state and provide evidence for the existence of decoherence-induced separability transitions that precisely coincide with the threshold for the feasibility of active error correction. A key insight is that local decoherence acting on the 'parent' cluster states of these models results in a Gibbs state. As an example, for the 2d (3d) toric code subjected to bit-flip errors, we show that the decohered density matrix can be written as a convex sum of SRE states for $p > p_c$, where $p_c$ is related to the paramagnetic-ferromagnetic transition in the 2d (3d) random-field bond Ising model along the Nishimori line.

Absence of barren plateaus in finite local-depth circuits with long-range entanglement
Hao-Kai Zhang, Shuo Liu, Shi-Xin Zhang
arXiv:2311.01393v4 Announce Type: replace-cross Abstract: Ground state preparation is classically intractable for general Hamiltonians. On quantum devices, shallow parameterized circuits can be effectively trained to obtain short-range entangled states under the paradigm of variational quantum eigensolver, while deep circuits are generally untrainable due to the barren plateau phenomenon. In this Letter, we give a general lower bound on the variance of circuit gradients for arbitrary quantum circuits composed of local 2-designs. Based on our unified framework, we prove the absence of barren plateaus in training finite local-depth circuits (FLDC) for the ground states of local Hamiltonians. FLDCs are allowed to be deep in the conventional circuit depth to generate long-range entangled ground states, such as topologically ordered states, but their local depths are finite, i.e., there is only a finite number of gates acting on individual qubits. This characteristic sets FLDC apart from shallow circuits: FLDC in general cannot be classically simulated to estimate local observables efficiently by existing tensor network methods in two and higher dimensions. We validate our analytical results with extensive numerical simulations and demonstrate the effectiveness of variational training using the generalized toric code model.

Convergence of Ginzburg-Landau expansions: superconductivity in the Bardeen-Cooper-Schrieffer theory and chiral symmetry breaking in the Nambu-Jona-Lasinio model
William Gyory, Naoki Yamamoto
arXiv:2312.16372v2 Announce Type: replace-cross Abstract: We study the convergence of the Ginzburg-Landau (GL) expansion in the context of the Bardeen-Cooper-Schrieffer (BCS) theory for superconductivity and the Nambu-Jona-Lasinio (NJL) model for chiral symmetry breaking at finite temperature $T$ and chemical potential $\mu$. We present derivations of the all-order formulas for the coefficients of the GL expansions in both systems under the mean-field approximation. We show that the convergence radii for the BCS gap $\Delta$ and dynamical quark mass $M$ are given by $\Delta_\text{conv} = \pi T$ and $M_\text{conv} = \sqrt{\mu^2 + (\pi T)^2}$, respectively. We also discuss the implications of these results and the quantitative reliability of the GL expansion near the first-order chiral phase transition.

First Hitting Times on a Quantum Computer: Tracking vs. Local Monitoring, Topological Effects, and Dark States
Qingyuan Wang, Silin Ren, Ruoyu Yin, Klaus Ziegler, Eli Barkai, Sabine Tornow
arXiv:2402.15843v2 Announce Type: replace-cross Abstract: We investigate a quantum walk on a ring represented by a directed triangle graph with complex edge weights and monitored at a constant rate until the quantum walker is detected. To this end, the first hitting time statistics is recorded using unitary dynamics interspersed stroboscopically by measurements, which is implemented on IBM quantum computers with a midcircuit readout option. Unlike classical hitting times, the statistical aspect of the problem depends on the way we construct the measured path, an effect that we quantify experimentally. First, we experimentally verify the theoretical prediction that the mean return time to a target state is quantized, with abrupt discontinuities found for specific sampling times and other control parameters, which has a well-known topological interpretation. Second, depending on the initial state, system parameters, and measurement protocol, the detection probability can be less than one or even zero, which is related to dark-state physics. Both, return-time quantization and the appearance of the dark states are related to degeneracies in the eigenvalues of the unitary time evolution operator. We conclude that, for the IBM quantum computer under study, the first hitting times of monitored quantum walks are resilient to noise. Yet, a finite number of measurements leads to broadening effects, which modify the topological quantization and chiral effects of the asymptotic theory with an infinite number of measurements. Our results point the way for the development of novel quantum walk algorithms that exploit measurement-induced effects on quantum computers.

Flows in the Space of Interacting Chiral Boson Theories
Stephen Ebert, Christian Ferko, Cian Luke Martin, Gabriele Tartaglino-Mazzucchelli
arXiv:2403.18242v2 Announce Type: replace-cross Abstract: We study interacting theories of $N$ left-moving and $\overline{N}$ right-moving Floreanini-Jackiw bosons in two dimensions. A parameterized family of such theories is shown to enjoy (non-manifest) Lorentz invariance if and only if its Lagrangian obeys a flow equation driven by a function of the energy-momentum tensor. We discuss the canonical quantization of such theories along classical stress tensor flows, focusing on the case of the root-$T \overline{T}$ deformation, where we obtain perturbative results for the deformed spectrum in a certain large-momentum limit. In the special case $N = \overline{N}$, we consider the quantum effective action for the root-$T \overline{T}$-deformed theory by expanding around a general classical background, and we find that the one-loop contribution vanishes for backgrounds with constant scalar gradients. Our analysis can also be interpreted via dual $U(1)$ Chern-Simons theories in three dimensions, which might be used to describe deformations of charged $\mathrm{AdS}_3$ black holes or quantum Hall systems.

Quantum computing topological invariants of two-dimensional quantum matter
Marcel Niedermeier, Marc Nairn, Christian Flindt, Jose L. Lado
arXiv:2404.06048v2 Announce Type: replace-cross Abstract: Quantum algorithms provide a potential strategy for solving computational problems that are intractable by classical means. Computing the topological invariants of topological matter is one central problem in research on quantum materials, and a variety of numerical approaches for this purpose have been developed. However, the complexity of quantum many-body Hamiltonians makes calculations of topological invariants challenging for interacting systems. Here, we present two quantum circuits for calculating Chern numbers of two-dimensional quantum matter on quantum computers. Both circuits combine a gate-based adiabatic time-evolution over the discretized Brillouin zone with particular phase estimation techniques. The first algorithm uses many qubits, and we analyze it using a tensor-network simulator of quantum circuits. The second circuit uses fewer qubits, and we implement it experimentally on a quantum computer based on superconducting qubits. Our results establish a method for computing topological invariants with quantum circuits, taking a step towards characterizing interacting topological quantum matter using quantum computers.

Found 7 papers in prb
Date of feed: Thu, 11 Apr 2024 03:17:27 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Subtlety of modes trapped by vortices in a topological superconducting heterostructure
Xin-Hai Tu, Xian-Gang Wan, and Ning Hao
Author(s): Xin-Hai Tu, Xian-Gang Wan, and Ning Hao

In a topological superconducting heterostructure comprising an $s$-wave superconductor and a semiconductor with Rashba spin-orbit coupling, several distinct modes emerge when an external magnetic field is applied: Majorana zero-energy modes, trivial Caroli–de Gennes–Matricon modes, and edge modes. W…

[Phys. Rev. B 109, 144512] Published Wed Apr 10, 2024

Thickness-dependent anisotropic superconductivity and charge density wave in ${\mathrm{ZrTe}}_{3}$ down to the two-dimensional limit
Xinyu Chen, Changsheng Zhu, Bin Lei, Weizhuang Zhuo, Wenxiang Wang, Jiaxiang Ma, Xigang Luo, Ziji Xiang, and Xianhui Chen
Author(s): Xinyu Chen, Changsheng Zhu, Bin Lei, Weizhuang Zhuo, Wenxiang Wang, Jiaxiang Ma, Xigang Luo, Ziji Xiang, and Xianhui Chen

Charge density waves (CDW) accompanied by superconductivity (SC) is an enduring topic in the field of condensed matter physics for it involves exotic physical properties and quantum states. This paper presents a competitive relationship between the anisotropic SC and CDW down to the two-dimensional limit in ZrTe3, a quasi-one-dimensional material. It reveals an unusual nonmonotonic evolution versus thickness and suggests a complicated superconducting mechanism in this compound.

[Phys. Rev. B 109, 144513] Published Wed Apr 10, 2024

Delicate semimetals: Protected gapless phases from unstable homotopies
Bhandaru Phani Parasar and Vijay B. Shenoy
Author(s): Bhandaru Phani Parasar and Vijay B. Shenoy

We construct and explore two-band topological semimetals in different spatial dimensions that are protected by unstable homotopies. Dubbed “delicate semimetals,” they generically host nodal lines and are inspired by the example of such phases realized in four dimensions arising from maps from the th…

[Phys. Rev. B 109, 155131] Published Wed Apr 10, 2024

Electronic and magnetotransport properties of twisted bilayer graphene in the presence of external electric and magnetic fields
Priyanka Sinha, Ayan Mondal, Simão Meneses João, and Bheema Lingam Chittari
Author(s): Priyanka Sinha, Ayan Mondal, Simão Meneses João, and Bheema Lingam Chittari

We investigate extensively the electronic and transport properties of twisted bilayer graphene when subjected to both an external perpendicular electric field and a magnetic field. Using a basic tight-binding model, we show the flat electronic band properties as well as the density of states (DOS), …

[Phys. Rev. B 109, 155412] Published Wed Apr 10, 2024

Resonant inelastic x-ray scattering of the ${J}_{\mathrm{eff}}=\frac{1}{2}$ Mott insulator $\mathrm{Sr}{}_{2}\mathrm{IrO}{}_{4}$ from density functional theory
V. N. Antonov, D. A. Kukusta, and L. V. Bekenov
Author(s): V. N. Antonov, D. A. Kukusta, and L. V. Bekenov

We have investigated the electronic structure of ${\mathrm{Sr}}_{2}{\mathrm{IrO}}_{4}$ within density functional theory using the generalized gradient approximation while considering strong Coulomb correlations in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital…

[Phys. Rev. B 109, 165120] Published Wed Apr 10, 2024

High-order harmonic generation in graphene quantum dots in the field of an elliptically polarized pulse
Suresh Gnawali and Vadym Apalkov
Author(s): Suresh Gnawali and Vadym Apalkov

We study theoretically the generation of high-order harmonics in graphene quantum dots placed in the field of an elliptically polarized ultrashort pulse. The generated high-order harmonics are sensitive to the pulse's ellipticity and its amplitude. The intensities of high-order harmonics become very…

[Phys. Rev. B 109, 165121] Published Wed Apr 10, 2024

Perfect intrinsic and nonlinear chirality simultaneously driven by half-integer topological charge
Shijie Cai, Jiafei Chen, Xiaoshan Liu, Guolan Fu, Guiqiang Liu, Jing Chen, Chaojun Tang, Wei Du, and Zhengqi Liu
Author(s): Shijie Cai, Jiafei Chen, Xiaoshan Liu, Guolan Fu, Guiqiang Liu, Jing Chen, Chaojun Tang, Wei Du, and Zhengqi Liu

Bound states in the continuum hold extraordinary optical topological properties and can significantly enhance the interaction between light and matter including the circular dichroism (CD) in chiral resonant metasurfaces. In this paper, we demonstrate the split and displacement of topological charge…

[Phys. Rev. B 109, 165420] Published Wed Apr 10, 2024

Found 1 papers in comm-phys

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Improved particle-flow event reconstruction with scalable neural networks for current and future particle detectors
Javier Duarte

Communications Physics, Published online: 10 April 2024; doi:10.1038/s42005-024-01599-5

The next generation of high energy particle colliders will have features that allows for highly granular detectors and current methods for particle collision reconstruction are limited. The authors explore machine learning algorithms for reconstructing events in electron-positron collisions for such future colliders obtaining a best-performing graph neural network that enhances the jet transverse momentum resolution by up to 50%, outperforming traditional methods and promising significant advancements in future collider measurements.

Found 4 papers in small
Date of feed: Wed, 10 Apr 2024 08:08:24 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Nanochannel Stability of Chemically Converted Graphene Oxide Membranes
Siyu Zhou, Kecheng Guan, Zhan Li, Ping Xu, Shang Fang, Aiwen Zhang, Zheng Wang, Shengnan He, Keizo Nakagawa, Hideto Matsuyama
Small, EarlyView.

Molecular Engineering to Regulate the Pseudo‐Graphitic Structure of Hard Carbon for Superior Sodium Energy Storage
Xiang Zhang, Zhidong Hou, Mingwei Jiang, Jiahui Peng, Honghao Ma, Yuyang Gao, Jian‐Gan Wang
Small, EarlyView.

Solution‐Processable Large‐Area Black Phosphorus/Reduced Graphene Oxide Schottky Junction for High‐Temperature Broadband Photodetectors
Yanan Zhou, Xue Yang, Ning Wang, Xiaojian Wang, Jiaxin Wang, Guangming Zhu, Qingliang Feng
Small, EarlyView.

High Thermoelectric Performance in Bismuth Telluride via Constructing MoSe2‐2D Heterojunction
Tao Xiong, Hailong He, Ge Tian, Hongrui Ren, Chunping Niu, Mengmeng Liu, Youqun Li, Yi Wu, Mingzhe Rong
Small, EarlyView.