A5050554734- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- Magnetic and transport properties of perovskites and related materials
- Quantum and electron transport phenomena
- Electronic and Structural Properties of Oxides
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Quantum Information and Cryptography
- Heusler alloys: electronic and magnetic properties
- Perovskite Materials and Applications
- Transition Metal Oxide Nanomaterials
- Intellectual Capital and Performance Analysis
- Inorganic Fluorides and Related Compounds
- Cold Atom Physics and Bose-Einstein Condensates
- Catalysis and Oxidation Reactions
- Corporate Taxation and Avoidance
- Organic and Molecular Conductors Research
- Quantum chaos and dynamical systems
- Statistical Mechanics and Entropy
- Neural Networks and Reservoir Computing
- Spectroscopy and Laser Applications
- ZnO doping and properties
- Organic Electronics and Photovoltaics
RIKEN
2024-2025
RIKEN Center for Emergent Matter Science
2023-2025
Nippon Soken (Japan)
2024
Centre National de la Recherche Scientifique
2019-2023
The University of Tokyo
2023
Centre de Physique Théorique
2018-2023
École Polytechnique
2018-2023
Collège de France
2022
Goethe University Frankfurt
2012-2018
Centre de Physique Théorique
2018
We use angle-resolved photo-emission spectroscopy (ARPES) to explore the electronic structure of single crystals FeSe over a wide range binding energies and study effects strong electron-electron correlations. provide evidence for existence "Hubbard-like bands" at high consisting incoherent many-body excitations originating from Fe $3d$ states in addition renormalized quasiparticle bands near Fermi level. Many energy features observed ARPES data can be accounted when incorporating local...
Motivated by the recent wealth of exotic magnetic phases emerging in two-dimensional frustrated lattices, we investigate origin possible magnetism monolayer family triangular lattice materials $MX_2$ ($M$={V, Mn, Ni}, $X$={Cl, Br, I}). We first show that consideration general properties such as filling and hybridization enables to formulate trends for most relevant interaction parameters. In particular, observe effects spin-orbit coupling (SOC) can be effectively tuned through ligand...
Abstract Motivated by reports of metallic behavior in the recently synthesized RuI 3 , contrast to Mott-insulating nature actively discussed α -RuCl as well RuBr we present a detailed comparative analysis electronic and magnetic properties this family trihalides. Using combination first-principles calculations effective-model considerations, conclude that similarly other two members, is most probably on verge Mott insulator, but with much smaller moments strong frustration. We predict ideal...
We study the effect of oxygen vacancies on electronic structure model strongly correlated metal SrVO$_3$. By means angle-resolved photoemission (ARPES) synchrotron experiments, we investigate systematic UV dose measured spectra. observe onset a spurious dose-dependent prominent peak at an energy range were lower Hubbard band has been previously reported in this compound, raising questions its previous interpretation. careful analysis dependent effects succeed disentangling contributions...
LiV2O4 is a member of the so-called 3d heavy fermion (HF) compounds, with effective electron mass exceeding 60 times free mass, comparable 4f HF compounds. The origin strong correlation in combination its metallic character have been subject intense theoretical and experimental discussion, Kondo-like Mott physics being suggested as physical origin. Here, we report state-of-the art ab initio density functional theory + dynamical mean-field calculations for full three-orbital V t2g manifold...
We investigate via LDA+DMFT (local density approximation combined with dynamical mean field theory) the manifestation of correlation effects in a wide range binding energies hole-doped family Fe-pnictides $A$Fe$_2$As$_2$ ($A={\rm K}$, Rb, Cs) as well fictitious FrFe$_2$As$_2$ and $a$-axis stretched CsFe$_2$As$_2$. This choice systems allows for systematic analysis interplay Hund's coupling $J_H$ on-site Coulomb repulsion $U$ multi-orbital under negative pressure. With increasing ionic size...
We investigate the role of nonlocal correlations in LiFeAs by exploring an ab initio--derived multiorbital Hubbard model for via two-particle self-consistent (TPSC) approach. The formulation TPSC approximates irreducible interaction vertex to be orbital-dependent constant, which is self-consistently determined from local spin and charge sum rules. Within this approach, we disentangle contribution show that approximation one recovers dynamical mean field theory result. comparison our...
Abstract Motivated by recent reports of a quantum-disordered ground state in the triangular lattice compound NaRuO 2 , we derive j eff = 1/2 magnetic model for this system means first-principles calculations. The pseudospin Hamiltonian is dominated bond-dependent off-diagonal Γ interactions, complemented ferromagnetic Heisenberg exchange and notably antiferromagnetic Kitaev term. In addition to bilinear find sizable four-spin ring contribution with strongly anisotropic character, which has...
Recent developments in quantum hardware and algorithms have made it possible to utilize the capabilities of current noisy intermediate-scale devices for addressing problems chemistry condensed matter physics. Here we report a demonstration solving dynamical mean-field theory (DMFT) impurity problem Hubbard-Holstein model on IBM 27-qubit Quantum Falcon Processor Kawasaki, including self-consistency DMFT equations. This opens up possibility investigate strongly correlated electron systems...
In this work we present a multi-orbital form of the Two-Particle Self-Consistent approach (TPSC), here effective local and static irreducible interaction vertices are determined by means Dynamical Mean-Field Theory (DMFT). This replaces approximate ansatz equations for double occupations $\langle n^{}_{\alpha,\sigma}n^{}_{\beta,\sigma'}\rangle$ sampling them directly same model using DMFT. Compared to usual Hartree-Fock like ansatz, leads more accurate in weakly correlated regime, provides...
We investigate the role of correlations in tetragonal and collapsed phases CaFe2As2 by performing charge self-consistent DFT+DMFT (density functional theory combined with dynamical mean-field theory) calculations. While topology Fermi surface is basically unaffected inclusion correlation effects, we find important orbital-dependent mass renormalizations which show good agreement recent angle-resolved photoemission (ARPES) experiments. Moreover, observe a markedly different behavior these...
In a common paradigm, the electronic structure of condensed matter is divided into weakly and strongly correlated compounds. While conventional band theory usually works well for former class, many-body effects are essential latter. Materials such as familiar ${\mathrm{SrTiO}}_{3}$ (STO) compound that bridge or even abandon this characterization scheme highly interesting. Here, it shown, by means combining density functional with dynamical mean-field theory, oxygen vacancies on STO (001)...
One of the most challenging problems in solid state systems is microscopic analysis electronic correlations. A paramount minimal model that encodes correlation effects Hubbard Hamiltonian, which -- albeit its simplicity exactly solvable only a few limiting cases and approximate many-body methods are required for solution. In this review we present an overview on non-perturbative Two-Particle Self-Consistent method (TPSC) was originally introduced to describe properties single-band model. We...
Recently, ${\mathrm{KFe}}_{2}{\mathrm{As}}_{2}$ was shown to exhibit a structural phase transition from tetragonal collapsed under an applied pressure of about 15 GPa. Surprisingly, the hosts superconducting state with ${T}_{c}\ensuremath{\sim}12\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, while is ${T}_{c}\ensuremath{\le}3.4\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ superconductor. We show that key difference between previously known nonsuperconducting in...
Starting from an ab initio-derived two-site dimer Hubbard Hamiltonian on a triangular lattice, we calculate the superconducting gap functions and critical temperatures for representative $\ensuremath{\kappa}\ensuremath{-}{(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF})}_{2}\mathrm{X}$ superconductors by solving linearized Eliashberg equation using two-particle self-consistent approach (TPSC) extended to multisite problems. Such extension allows inclusion of molecule degrees freedom in description...
Abstract Materials displaying metal-insulator transitions (MITs) as a function of external parameters such temperature, pressure, or composition are most intriguing from the fundamental point view and also hold high promise for applications. Vanadium dioxide (VO 2 ) is one prominent examples MIT having prospective applications ranging intelligent coatings, infrared sensing, imaging, to Mott memory neuromorphic devices. The key aspects conditioning possible controllability reversibility...
Recent density functional theory (DFT) calculations for KFe2As2 have been shown to be insufficient satisfactorily describe angle-resolved photoemission (ARPES) measurements as well observed de Haas–van Alphen (dHvA) frequencies. In the present work, we extend DFT based on full-potential linear augmented plane-wave method by dynamical mean field (DFT+DMFT) include correlation effects beyond local approximation. We results two sets of reported crystal structures. Our indicate that is a...
The discovery of iron pnictides and chalcogenides as a new class unconventional superconductors in 2008 has generated an enourmous amount experimental theoretical work that identifies these materials correlated metals with multiorbital physics, where magnetism, nematicity superconductivity are competing phases appear function pressure doping. A microscopic understanding the appearance is crucial order to determine nature systems. Here we review our recent efforts describe understand from...
We have investigated the charge transfer mechanism in single crystals of DTBDT-TCNQ and DTBDT-F4TCNQ (where DTBDT is dithieno[2,3-d;2',3'-d'] benzo[1,2-b;4,5-b']dithiophene) using a combination near-edge X-ray absorption spectroscopy (NEXAFS) density functional theory calculations (DFT) including final state effects beyond sudden approximation. In particular, we find that description considers partial screening electron-hole Coulomb correlation on static level as well rearrangement...
Motivated by the intriguing physics of quasi-two-dimensional fermionic systems, such as high-temperature superconducting oxides, layered transition metal chalcogenides, or surface interface development many-body computational methods geared at including both local and nonlocal electronic correlations has become a rapidly evolving field. It been realized, however, that success can be hampered emergence noncausal features in effective observable quantities involved. Here, we present an...
We study the temperature and pressure dependence of structural electronic properties iron pnictide superconductor BaFe2As2. use density functional theory based Born-Oppenheimer molecular dynamics simulations to investigate system at temperatures from T=5 K 150 pressures P=0 GPa 30 GPa. When increasing low temperature, we find two transitions an orthorhombic a tetragonal collapsed structure that are also observed in zero relaxations experiment. However, these considerably smeared out finite...
The attractive interaction in conventional BCS superconductors is provided by a bosonic mode. However, the pairing glue of most unconventional unknown. effect electron-boson coupling therefore extensively studied these materials. A key signature are dispersion kinks that can be observed spectral function as abrupt changes velocity and lifetime quasiparticles. Here, we show existence two iron-based superconductor RbFe$_2$As$_2$ using angle-resolved photoemission spectroscopy (ARPES) dynamical...
The attractive interaction in conventional BCS superconductors is provided by a bosonic mode. However, the pairing glue of most unconventional unknown. effect electron-boson coupling therefore extensively studied these materials. A key signature dispersion kinks that can be observed spectral function as abrupt changes velocity and lifetime quasiparticles. Here, we show existence two iron-based superconductor RbFe2As2 using angle-resolved photoemission spectroscopy (ARPES) dynamical mean...
LiV$_2$O$_4$ is a member of the so-called $3d$ heavy fermion compounds, with effective electron mass exceeding 60 times free mass, comparable to $4f$ compounds. The origin strong correlation in combination its metallic character have been subject intense theoretical and experimental discussion, Kondo-like physics Mott-physics being suggested as physical origin. Here we report state-of-the art \textit{ab initio} Density Functional Theory + dynamical mean-field theory calculations for full...
Recent developments in quantum hardware and algorithms have made it possible to utilize the capabilities of current noisy intermediate-scale devices for addressing problems chemistry condensed matter physics. Here we report a demonstration solving dynamical mean-field theory (DMFT) impurity problem Hubbard-Holstein model on IBM 27-qubit Quantum Falcon Processor Kawasaki, including self-consistency DMFT equations. This opens up possibility investigate strongly correlated electron systems...