A5055847843- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- Quantum and electron transport phenomena
- Superconductivity in MgB2 and Alloys
- Electronic and Structural Properties of Oxides
- Advanced Chemical Physics Studies
- Magnetic properties of thin films
- Cold Atom Physics and Bose-Einstein Condensates
- Solid-state spectroscopy and crystallography
- Molecular Junctions and Nanostructures
- Semiconductor Quantum Structures and Devices
- Organic Electronics and Photovoltaics
- Organic and Molecular Conductors Research
- Topological Materials and Phenomena
- Quantum, superfluid, helium dynamics
- High-pressure geophysics and materials
- Thermodynamic and Structural Properties of Metals and Alloys
- Quantum optics and atomic interactions
- Iron-based superconductors research
- Guidance and Control Systems
- Inorganic Fluorides and Related Compounds
- Theoretical and Computational Physics
- Phase-change materials and chalcogenides
University of Antwerp
2024
Belarusian State Economic University
2024
RIKEN Center for Emergent Matter Science
2014-2023
University of Michigan
2022
Kurchatov Institute
2010-2020
National University Zaporizhzhia Polytechnic
2015
RIKEN
2008-2012
RIKEN Advanced Science Institute
2012
Japan Science and Technology Agency
2003-2007
National Institute of Advanced Industrial Science and Technology
2002-2007
A detailed study of the Fr\"ohlich polaron model is performed on basis diagrammatic quantum Monte Carlo method [N. V. Prokof'ev and B. Svistunov, Phys. Rev. Lett. $81,$ 2514 (1998)]. The further developed both quantitatively (performance) qualitatively (new estimators), enhanced by spectral analysis Green's function, within an approach in present paper. We up to date results for binding energy, make available precise data effective mass, including region intermediate strong couplings. look...
We present numeric results for ground state and angle resolved photoemission spectra (ARPES) single hole in t-J model coupled to optical phonons. The systematic-error free diagrammatic Monte Carlo is employed where the Feynman graphs Matsubara Green function imaginary time are summed up completely with respect phonons variables, while magnetic variables subjected non-crossing approximation. obtain that at electron-phonon coupling constants relevant high Tc cuprates polaron undergoes...
Interplay of spin, charge, orbital and lattice degrees freedom in oxide heterostructures results a plethora fascinating properties, which can be exploited new generations electronic devices with enhanced functionalities. The paradigm example is the interface between two band insulators LaAlO3 SrTiO3 (LAO/STO) that hosts two-dimensional electron system (2DES). Apart from mobile charge carriers, this exhibits range intriguing properties such as field effect, superconductivity ferromagnetism,...
We study a single polaron in the Su-Schrieffer-Heeger (SSH) model using four different techniques (three numerical and one analytical). Polarons show smooth crossover from weak to strong coupling, as function of electron-phonon coupling strength λ, all models where this depends only on phonon momentum q. In SSH also electron k; we find it has sharp transition, at critical λ(c), between states with zero nonzero ground state. All other properties are singular λ=λ(c). This result is...
Abstract Second-order continuous phase transitions are characterized by symmetry breaking with order parameters. Topological orders of electrons, the topological index defined in momentum space, provide a distinct perspective for transitions, which categorized as quantum not being accompanied breaking. However, there still limited observations counterparts real space. Here we show real-space transition chiral magnet MnGe, hosting periodic array hedgehog and antihedgehog spin singularities....
We formulate the problem of numerical analytic continuation in a way that lets us draw meaningful conclusions about properties spectral function based solely on input data. Apart from ensuring consistency with data (within their error bars) and priori posteriori (conditional) constraints, it is crucial to reliably characterize accuracy---or even ambiguity---of output. explain how these challenges can be met two approaches: stochastic optimization consistent constraints modified maximum...
The charge dynamics in weakly hole doped high temperature superconductors is studied terms of the accurate numerical solution to a model single interacting with quantum lattice an antiferromagnetic background, and far-infrared ellipsometry measurements. experimentally observed two electronic bands infrared spectrum can be identified interplay between electron correlation electron-phonon interaction resolving long standing mystery midinfrared band.
The spectral response and physical features of the 2D Hubbard-Holstein model are calculated both in equilibrium at zero low chemical dopings, after an ultra short powerful light pulse, undoped systems. At strong charge-lattice couplings, optical conductivity reveals a 3-peak structure agreement with experimental observations. After pulse nonzero electron-phonon interaction, phonon spin subsystems oscillate period $T_{ph} \approx 80$ fs. decay time oscillations is about 150-200 fs, similar to...
We developed a novel method for obtaining the distribution of trapped carriers over their degree localization in organic transistors, based on fine analysis electron spin resonance spectra at low enough temperatures where all are localized. To apply to pentacene thin-film we proved through continuous wave saturation experiments that localized below 50 K. analyzed 20 K and found major groups traps comprise states having functions spanning around 1.5 5 molecules with spatial extent range...
We introduce the first bold diagrammatic Monte Carlo approach to deal with polaron problems at a finite electron density nonperturbatively, i.e., by including vertex corrections high orders. Using Holstein model on square lattice as prototypical example, we demonstrate that our method is capable of providing accurate results in thermodynamic limit all regimes from renormalized Fermi liquid single polaron, across nonadiabatic region where and Debye energies are same order magnitude. By...
We present the first unbiased results for mobility μ of a one-dimensional Holstein polaron obtained by numerical analytic continuation combined with diagrammatic and worldline Monte Carlo methods in thermodynamic limit. have identified time several distinct regimes λ-T plane including band conduction region, incoherent metallic an activated hopping high-temperature saturation region. observe that although mobilities mean free paths at different values λ differ many orders magnitude small...
We present controlled numerical results for the ground-state spectral function of resonant Fermi polaron in three dimensions. establish existence a ``dark continuum''---a region anomalously low weight between narrow peak and rest continuum. The dark continuum develops when $s$-wave scattering length is order inverse wave vector, $a\ensuremath{\lesssim}1/{k}_{\mathrm{F}}$, i.e., absence small interaction-related parameter not expected to feature near-perfect gap structure after peak.
Abstract Anomalous Hall effect, a manifestation of effect occurring in systems without time-reversal symmetry, has been mostly observed ferromagnetically ordered materials. However, its realization high-mobility two-dimensional electron system remains elusive, as the incorporation magnetic moments deteriorates device performance compared to non-doped structure. Here we observe systematic emergence anomalous various MgZnO/ZnO heterostructures that exhibit quantum effect. At low temperatures,...
All acoustic and the lowest optic branches in three main symmetry directions have been determined by inelastic neutron scattering at room temperature using a double isotope monocrystal 154Sm11B6. In comparison with integer valence system LaB6 phonons are softer, LA exhibit remarkable anomalies. These features interpreted on basis of specific coupling lattice vibrations dipole (f-d) monopole (f-f) excitations Sm shells, latter being characteristic for mixed semiconductor. A weak broad signal...
Electronic structure of the three-dimensional colossal magnetoresistive perovskite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ has been established using soft-x-ray angle-resolved photoemission spectroscopy with its intrinsically sharp definition electron momentum. The experimental results show much weaker polaronic coupling compared to bilayer manganites and are consistent theoretical band including empirical Hubbard parameter U. Fermi surface unveils canonical...
GPT-4o is an autoregressive omni model that accepts as input any combination of text, audio, image, and video, generates image outputs. It's trained end-to-end across vision, meaning all inputs outputs are processed by the same neural network. can respond to audio in little 232 milliseconds, with average 320 which similar human response time conversation. It matches GPT-4 Turbo performance on text English code, significant improvement non-English languages, while also being much faster 50\%...
Worm algorithm quantum Monte Carlo simulations of the hole Green function with subsequent spectral analysis were performed for J/t 0.1, 0.2, 0.4 on lattices up to LxL=32x32 sites at temperatures as low T=J/40, and present, apparently, in thermodynamic limit. Spectral reveals a delta-function-sharp quasiparticle peak lower edge spectrum which is incompatible power-law singularity thus rules out possibility spin-charge separation this parameter range. continuum features two peaks separated by gap ~4t.
An explanation of the origin inelastic peaks in magnetic neutron-scattering spectra mixed-valence semiconductor SmB6 is proposed. It shown that excitonic theory intermediate valence state not only gives value peak frequency but also explains unusual angular dependence intensity scattering and describes dispersion excitations good agreement with experiment.
We present accurate results for optical conductivity of the three dimensional Fröhlich polaron in all coupling regimes. The systematic-error free diagrammatic quantum Monte Carlo method is employed where Feynman graphs momentum-momentum correlation function imaginary time are summed up. real-frequency obtained by analytic continuation with stochastic optimization. compare numerical data available perturbative and nonperturbative approaches to show that picture sharp resonances due relaxed...
Results indicating the important role of electron–phonon coupling in high-temperature superconductivity compounds are presented, with emphasis on its implications for angle-resolved photoemission and optical conductivity. The dimensionless phonon constant λ is determined by comparing experimental theoretical results. Although undoped materials strong-coupling (λ ~ 1) regime, hole doping decreases λ, bringing to intermediate-coupling regime at optimum concentrations.
The transport properties at finite temperature of crystalline organic semiconductors are investigated, within the Su-Schrieffer-Heeger model, by combining an exact diagonalization technique, Monte Carlo approaches, and a maximum entropy method. temperature-dependent mobility data measured in single crystals rubrene successfully reproduced: crossover from super- to subdiffusive motion occurs range $150\ensuremath{\le}T\ensuremath{\le}200\text{ }\text{ }\mathrm{K}$, where mean free path...
In a number of physical situations, from polarons to Dirac liquids and non-Fermi liquids, one encounters the "beyond quasiparticles" regime, in which inelastic scattering rate exceeds thermal energy quasiparticles. Transport this regime cannot be described by kinetic equation. We employ diagrammatic Monte Carlo method study mobility Fröhlich polaron discover nonperturbative effects: strong violation Mott-Ioffe-Regel criterion at intermediate couplings, minimum T∼Ω strong-coupling limit (Ω is...
Abstract Many transition metal oxides (TMOs) are Mott insulators due to strong Coulomb repulsion between electrons, and exhibit metal-insulator transitions (MITs) whose mechanisms not always fully understood. Unlike most TMOs, minute doping in CaMnO 3 induces a metallic state without any structural transformations. This material is thus an ideal platform explore band formation through the MIT. Here, we use angle-resolved photoemission spectroscopy visualize how electrons delocalize couple...
We develop a novel self-consistent approach for studying the angle resolved photoemission spectra (ARPES) of hole in t-J Holstein model giving perfect agreement with numerically exact diagrammatic Monte Carlo (DMC) data at zero temperature all regimes electron-phonon coupling. Generalizing to finite temperatures, we find that anomalous dependence ARPES undoped cuprates is explained by cooperative interplay coupling magnetic fluctuations and strong interaction.