FieldsElectronic transport in condensed matter

Exploring Electronic States in BEDT-TTF Organic Superconductors

This review, published in the Journal of the Physical Society of Japan, provides a comprehensive summary of the electronic states observed in BEDT-TTF type organic superconductors, including metal-insulator transitions, Mottness transitions, non-Fermi liquids, quantum spin liquids, and Bose-Einstein condensation.

Superconductivity

Electronic transport in condensed matter

Magnetic properties in condensed matter

Conversion of Chiral Phonons into Magnons in Magnets

A new phenomenon involving the conversion of chiral phonons into magnons is theoretically predicted. The effective magnetic field induced by chiral phonons causes a change in the spin magnetization of magnets.

Electronic transport in condensed matter

Variety of Mechanically Induced Spin Currents in Rashba Systems

Various types of spin currents, including unconventional types, are generated in Rashba spin-orbit coupled systems by dynamic lattice distortions associated with, for example, surface acoustic waves.

Electronic transport in condensed matter

Magnetic properties in condensed matter

Structure and mechanical and thermal properties in condensed matter

What Determines the Sign of Spin Current? ~ Theoretical Study of Spin Seebeck Effect in Antiferromagnetic Insulators

We developed a microscopic theory for the spin Seebeck effect in antiferromagnets, that explains the sign reversal of the spin current at the spin-flop transition point and describes the sorts of dominant carriers.

Electronic transport in condensed matter

Chiral Anomalies in Organic Dirac Semimetals

A three-dimensional massless Dirac fermion system exhibiting broken chiral symmetry was successfully realized in organic conductor α-(BEDT-TTF)₂I₃ under high pressures. Our study detected the chiral anomaly-induced negative magnetoresistance and planar Hall effects and opened new avenues for further advancements in the field.

Electronic transport in condensed matter

Thermodynamic Property of a CMOS Device beyond Landauer Limit

Focusing on a CMOS NAND GATE operating in a sub-threshold region, the thermodynamic cost of computation was analyzed in relation to input/output voltages surpassing the Landauer limit.

Statistical physics and thermodynamics

Electronic transport in condensed matter

Cross-disciplinary physics and related areas of science and technology

Geometry-Based Nonlinear and Nonequilibrium Phenomena in Solids

Researchers from The University of Tokyo have recently reviewed geometric aspects of nonlinear and nonequilibrium optical phenomena for advanced materials applications in novel solar panels, photodetectors, diodes, and quantum computing.

Electronic structure and electrical properties of surfaces and nanostructures

Dielectric, optical, and other properties in condensed matter

Electronic transport in condensed matter

Quantum Hall Effect in Bulk (Multilayered) Organic Crystal

The multilayer quantum Hall effect is discovered in an organic massless Dirac electron system, α-(BETS)₂I₃ under pressure at low temperatures and a magnetic field of approximately 1 T.

Electronic structure and electrical properties of surfaces and nanostructures

Electronic transport in condensed matter

High Magnetic Field as a Tool for Discovery in Condensed Matter Physics

The Journal of the Physical Society of Japan highlights in this special topic recent advances in modern physics that have been realized with the generation of pulsed high magnetic fields.

Magnetic properties in condensed matter

Dielectric, optical, and other properties in condensed matter

Electronic transport in condensed matter

Structure and mechanical and thermal properties in condensed matter

Electron states in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Measurement, instrumentation, and techniques

Strange Metal Behavior Potentially Associated to Hidden Electronic Nematicity

Iron-based superconductor, Ba_1-xRb_xFe₂As₂, exhibits “strange metal” behavior—linear dependence of resistivity on temperature. It seems that hidden electronic nematic fluctuations play a greater role than the well-known antiferromagnetic fluctuations.

Superconductivity

Electronic transport in condensed matter

Thermoelectric Response in Strongly Disordered Systems

Based on the Kubo–Luttinger linear response theory, we discovered that the low-T Seebeck coefficient for Mott variable-range hopping in a d-dimensional system varies as S ∝ T^d/(d+1), which is different from the conventional S ∝ T^{(d−1)/(d+1)}. In addition, the experimental data for S of CuCrTiS₄ at low T are in excellent agreement with our prediction S ∝ T^3/4 (d = 3).

Electronic transport in condensed matter

Spin Transport in a Two-Dimensional Tilted Dirac Electron System

We propose that spin current in an organic conductor, α-(BETS)₂I₃, is an appropriate physical quantity to detect the topological nature of the material whose electrons obey a quasi-two-dimensional Dirac equation.

Electronic transport in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Violation of Fluctuation-Dissipation Theorem Results in Robustness of Fluctuation Against Localization

We study equilibrium current fluctuations in systems without time-reversal symmetry, violating the fluctuation-dissipation theorem. Notably, the off-diagonal fluctuation is insensitive to system imperfections in contrast to other fluctuations and conductivity.

Statistical physics and thermodynamics

Electronic transport in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Topological Aspects of a Nonlinear System: The Dimerized Toda Lattice

A nonlinear topological phase is shown to emerge in the dimerized Toda lattice. It is experimentally detectable by measuring the voltage propagation in electric circuits.

Electronic structure and electrical properties of surfaces and nanostructures

Electronic transport in condensed matter

Unusual Nonlinear Conductivity in Charge-Ordered α-(BEDT-TTF)₂I₃

Unusual nonlinear conduction is detected in organic molecular salt α-(BEDT-TTF)₂I₃. The observed third-order nonlinear conductivity implies a quadrupole instability hidden in this charge-ordered organic salt.

Electronic transport in condensed matter

New Systematic Analysis Method of Identifying Microscopic Essential Couplings

We propose a systematic method of identifying essential model parameters for nonlinear response tensors. The analysis results reveal fundamental couplings in nontrivial responses and promote further development of multiferroic responses.

Electronic transport in condensed matter

Dielectric, optical, and other properties in condensed matter

Cross-disciplinary physics and related areas of science and technology

Twist in the Tale: Exploring the Dielectric Screening Effect in Twisted Bilayer Graphene

Although the screening of an external electric field, strongly influences the electronic states of two-dimensional material stack, it is not well understood. Magnetotransport measurements of twisted double bilayer graphene uncovered the screening of atomic layers.

Electronic structure and electrical properties of surfaces and nanostructures

Electronic transport in condensed matter

Spin-Wave Dynamics in Antiferromagnets under Electric Current

Electric current causes a Doppler effect in spin waves in ferromagnets through a spin-transfer torque. We report that antiferromagnets allow two such spin-transfer torques and present a microscopic analysis that interpolates ferro- and antiferromagnetic transport regimes.

Electronic transport in condensed matter

Magnetic properties in condensed matter

Materials with Dirac Loops: A Potential Solution for Next-generation Electronics

A high-quality single crystal of rhenium oxide shows significantly large magnetoresistance, potentially originating from a unique electronic structure called “hourglass Dirac chain” protected by the symmetry of the crystal.

Electronic transport in condensed matter

Electron states in condensed matter

Measurements and Implications of Shot Noise in Mesoscopic Systems

Shot noise measurements provide rewarding insights into system properties, non-equilibrium phenomena, and quantum effects in mesoscopic systems.

Electronic transport in condensed matter

Magnetic properties in condensed matter

Superconductivity

Exploring the Thermoelectric Properties of Nitrogen-doped Carbon Nanotubes

A semiconducting carbon nanotube doped with an optimal concentration of nitrogen delivered a thermoelectric power substantially higher than that delivered by commercial Bi₂Te₃ alloys.

Electronic transport in condensed matter

Structure and mechanical and thermal properties in condensed matter

Cross-disciplinary physics and related areas of science and technology

Finding Pattern in Randomness: Brownian Motion of Skyrmions

The chiral properties of the Brownian motion of magnetic skyrmions in one- and two-dimensional systems in thermal equilibrium are reported.

Structure and mechanical and thermal properties in condensed matter

Electronic transport in condensed matter

Magnetic properties in condensed matter

Nonlinear Thermoelectric Transport Will Open a New and Exotic Way to Detect Topological Nature of Dirac Electrons in Solids

Recently, it was proposed that a novel nonlinear anomalous Ettingshausen effect enabled a new and exotic approach to observe topological nature of Dirac electrons in solids using thermoelectric properties.

Electronic transport in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Structure and mechanical and thermal properties in condensed matter

Semiconductor to Semimetal to Superconductor: An Excitonic Journey

A phase diagram was constructed for Ta₂NiSe₅, a promising candidate for excitonic insulators, using high pressure as a tuning parameter. The results indicated pressure-induced superconductivity in the semimetallic phase.

Superconductivity

Electronic transport in condensed matter

Exploring the Physics of Ferrimagnets for Future Spintronics Applications

This Special Topics collection of the Journal of the Physical Society of Japan covers recent progress in spintronics research on ferrimagnetic materials.

Structure and mechanical and thermal properties in condensed matter

Electronic transport in condensed matter

Magnetic properties in condensed matter

Cross-disciplinary physics and related areas of science and technology

Overlooked Materials Host Rich Physics of Strongly Correlated Electrons

An international team of researchers reviews the research progress on strongly spin-orbit coupled systems, providing an overview of theoretically predicted electronic phases, candidate materials, and unusual experimental observations.

Electron states in condensed matter

Magnetic properties in condensed matter

Electronic transport in condensed matter

How a Potentially Novel Effect Converts AC Current into DC Heat Flow

A novel current-induced thermoelectric phenomenon, the nonlinear anomalous Ettingshausen effect, was discussed. As an example, the weak charge ordering state in an organic conductor α-(BEDT-TTF)₂I₃ was focused on. This effect generates a transverse heat current with rectifying characteristics, namely unidirectionality even under AC fields.

Electronic transport in condensed matter

Electronic structure and electrical properties of surfaces and nanostructures

Structure and mechanical and thermal properties in condensed matter

Random Numbers Can Help Solve Difficult Problems in Many-body Physics

Theorists review a random state vector-based description of quantum many-body systems which helps greatly reduce the computational burden involved in their numerical simulations, opening doors to applications in quantum computing.

Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling

Electronic transport in condensed matter

Magnetic properties in condensed matter

No Mass Gap Phase Transition in Novel Massless Dirac Fermion Material

Using an organic massless Dirac fermion system, we found that massless Dirac fermions undergo a quantum phase transition without creating any mass gap even in the strong coupling regime.

Electron states in condensed matter

Electronic transport in condensed matter

What Dictates Nonlinear Behavior in Strongly Correlated Insulators?

The nonlinear conduction (the deviation from Ohm's law) has been discovered universally in various correlated materials. This may be explained by the percolation conduction in disordered materials.

Electronic transport in condensed matter

Statistical physics and thermodynamics