Year2021

New Classification Theory for Topological Gapless Superconducting Nodes
20211228
A new classification theory on topological superconducting gap nodes predicts two new gap structures emerging from a nonsymmorphic crystal symmetry and angular momentum.
Superconductivity

A Twostep Creation of Phonon Entanglement with Quantized Light
20211228
Dynamics of photoinduced quantum entanglement generation between phonons is theoretically revealed. The results contribute to the study of fundamental theoretical problems within quantum dynamics of photoinduced phase transitions and quantum information science.
Dielectric, optical, and other properties in condensed matter
Electromagnetism, optics, acoustics, heat transfer, and classical and fluid mechanics
Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling

SpinWave Dynamics in Antiferromagnets under Electric Current
20211228
Electric current causes a Doppler effect in spin waves in ferromagnets through a spintransfer torque. We report that antiferromagnets allow two such spintransfer torques and present a microscopic analysis that interpolates ferro and antiferromagnetic transport regimes.
Electronic transport in condensed matter
Magnetic properties in condensed matter

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Exploring the Basic Principles and Functionalities of Spintronic Thermal Management
20211213
Scientists propose a new spin caloritronics concept called “spintronic thermal management” and provide a comprehensive overview of basic principles, physical behaviors, and heat control functionalities associated with the concept.
Magnetic properties in condensed matter
Structure and mechanical and thermal properties in condensed matter

How Good is the TransitionState Theory?
20211130
For the first time, the main assumption of the transitionstate theory for the decay of complex quantum systems across a potential barrier was realized using a microscopic manybody Hamiltonian.
Statistical physics and thermodynamics
Nuclear physics

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Understanding Phase Transitions in Supersymmetric Quantum Electrodynamics With Resurgence Theory
20211125
Using resurgence theory to describe phase transitions in quantum field theory shows that information on nonperturbative effects like phase transitions can be obtained from a perturbative series expansion.
Theoretical Particle Physics

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The Mysteries of Charge Order and Charge Fluctuations in Cuprate Superconductors
20211116
This Special Topics issue condenses the latest research on the enigmatic characteristics of hightemperature superconductivity in cuprates through the observation and elucidation of charge order, charge fluctuations, and other phenomena.
Superconductivity
Dielectric, optical, and other properties in condensed matter
Structure and mechanical and thermal properties in condensed matter
Magnetic properties in condensed matter

Analyzing Photoinduced Phase Transitions in an Organic Salt Using Floquet Theory
2021115
Rich nonequilibrium phase diagrams, including photoinduced topological insulator phases, were theoretically predicted for an organic salt α(BEDTTTF)_{2}I_{3} when irradiated by elliptically polarized light.
Electronic structure and electrical properties of surfaces and nanostructures
Dielectric, optical, and other properties in condensed matter

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A New Look at Our Universe with Gravitational Wave Astronomy
20211026
A new interdisciplinary collaborative project underscores the importance of combining theory with advanced observation techniques to understand gravitational waves and their sources, opening doors to new discoveries about the universe.
Astrophysics, cosmology, and geophysics

Materials with Dirac Loops: A Potential Solution for Nextgeneration Electronics
20211014
A highquality 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

Electronic Structure Transformation in a Magnetized Topological Semimetal
2021106
We theoretically show that the nodal structures in topological semimetals, including Weyl points and nodal lines, can be switched by magnetic orders, accompanied by localized states at magnetic domain walls.
Electronic structure and electrical properties of surfaces and nanostructures

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Estimating Beta Decay Rates Better for Exotic Nuclei
2021101
Physicists from Japan demonstrate an improved estimation of the beta decay rate in heavy nuclei by considering nexttoleadingorder approximation for the electron wave function distorted by the Coulomb potential.
Nuclear physics

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Measurements and Implications of Shot Noise in Mesoscopic Systems
2021929
Shot noise measurements provide rewarding insights into system properties, nonequilibrium phenomena, and quantum effects in mesoscopic systems.
Electronic transport in condensed matter
Magnetic properties in condensed matter
Superconductivity

Exploring the Thermoelectric Properties of Nitrogendoped Carbon Nanotubes
2021929
A semiconducting carbon nanotube doped with an optimal concentration of nitrogen delivered a thermoelectric power substantially higher than that delivered by commercial Bi_{2}Te_{3} alloys.
Electronic transport in condensed matter
Structure and mechanical and thermal properties in condensed matter
Crossdisciplinary physics and related areas of science and technology

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Designing a New Spaceborne Interferometer to Probe the History of Our Universe
2021922
Scientists present a new design for a spaceborn laser interferometer that could detect gravitational waves below 10 Hz, letting us probe into new astrophysical phenomena.
Astrophysics, cosmology, and geophysics

Finding Pattern in Randomness: Brownian Motion of Skyrmions
202197
The chiral properties of the Brownian motion of magnetic skyrmions in one and twodimensional 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

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Generalizing Poisson Algebra with Geometry
202196
Using a differential geometric interpretation of Hamiltonian mechanics, a generalized Poisson bracket formulation is developed for a threedimensional phase space characterized by a triplet of canonical variables.
Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling

Nonlinear Thermoelectric Transport Will Open a New and Exotic Way to Detect Topological Nature of Dirac Electrons in Solids
2021825
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
2021816
A phase diagram was constructed for Ta_{2}NiSe_{5}, a promising candidate for excitonic insulators, using high pressure as a tuning parameter. The results indicated pressureinduced superconductivity in the semimetallic phase.
Superconductivity
Electronic transport in condensed matter

Exploring the Physics of Ferrimagnets for Future Spintronics Applications
202186
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
Crossdisciplinary physics and related areas of science and technology

Understanding Skyrmion Crystal Formation in EuPtSi
202182
We theoretically demonstrate that the interplay between the spincharge and spinorbit couplings in itinerant magnets stabilizes fielddirection sensitive, shortperiod skyrmions. Our results can aid in engineering shortperiod skyrmions.
Magnetic properties in condensed matter

Will Magnetic Properties near Pressure Induced Quantum Critical Phenomena Be Elucidated?
2021726
Hiraoka et al. developed an opposed anviltype pressure cell for magnetization measurements which combines a large sample space and is capable of generating higher pressures up to 6.3 GPa.
Measurement, instrumentation, and techniques
Magnetic properties in condensed matter

PTEP SPECIAL SECTION
Atoms Trapped with Light Behave Like a Dissipative Quantum System
2021719
A team of researchers from Japan experimentally realize, for the first time, a dissipative, paritytime symmetric, manybody quantum system from ultracold atoms trapped in an optical lattice.
Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling
Gases, plasmas, electric discharges, and beams

PTEP SPECIAL SECTION
Nonreal Energies with Real Effects in Exotic Condensed Matter Systems
2021719
Scientists demonstrate the presence of nonHermitian topological properties preserved under continuous physical deformations in strongly correlated systems in equilibrium, resulting from shortlived quanta of collective excitations.
Electron states in condensed matter

PTEP SPECIAL SECTION
A Quantum Description of Physical Systems with Nonreal Energies
2021719
While quantum systems are traditionally described by Hermitian Hamiltonians, the formalism is extendable to a nonHermitian description for systems that are dissipative or obey paritytime symmetry.
Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling
Nuclear physics
Electron states in condensed matter
Gases, plasmas, electric discharges, and beams

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Using Pulsed Cold Neutrons to Measure Neutron Lifetime
2021713
Scientists measure the lifetime of a neutron with pulsed neutron beams to explore the cause of a puzzling discrepancy in their previously measured lifetime.
Elementary particles, fields, and strings

Uncovering the Superlattice Structure of Calcium Iridium Oxide at Phase Transition
202179
Order parameter of nonmagnetic phase transition at 105 K, which is called "hidden order", was revealed in spinorbit coupled iridate Ca_{5}Ir_{3}O_{12}. This discover of order parameter with rotational and directional degrees of freedom in atomic scale will lead to development of energy saving devices with a fast crosscorrelated response.
Electron states in condensed matter
Structure and mechanical and thermal properties in condensed matter

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Overlooked Materials Host Rich Physics of Strongly Correlated Electrons
202172
An international team of researchers reviews the research progress on strongly spinorbit 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

Detecting Weak Quantum Magnetism at High Pressures
2021615
Improved device and method to measure magnetization under high pressure was developed, which brings a quick tool to screen phases of interest in weakly magnetic materials including quantum magnets.
Measurement, instrumentation, and techniques
Magnetic properties in condensed matter

Exotic Superconducting States in Transition Metal Tellurides
2021610
Nb_{2}Pd_{3}Te_{5} was found to show bulk superconductivity at 3.3 K. In contrast, Ta_{2}Pd_{3}Te_{5}, a 5d analogue of Nb_{2}Pd_{3}Te_{5}, showed nonmetallic electronic conduction, which was changed to show bulk superconductivity by chemical doping.
Superconductivity

Descriptor of Thermogalvanic Cell for Wasteheat Harvesting
2021531
The scaling relation between the Seebeck coefficient and solvent viscosity would enable for the design of improved thermogalvanic cells.
Structure and mechanical and thermal properties in condensed matter

How a Potentially Novel Effect Converts AC Current into DC Heat Flow
2021524
A novel currentinduced thermoelectric phenomenon, the nonlinear anomalous Ettingshausen effect, was discussed. As an example, the weak charge ordering state in an organic conductor α(BEDTTTF)_{2}I_{3} 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

Electric Quadrupole Orders in fElectron Systems on the fcc Lattice
2021517
We theoretically showed that electric quadrupoles in some heavy fermion materials exhibit a very rich phase diagram including unique partiallyordered phases stabilized by an interaction specific to these systems.
Magnetic properties in condensed matter
Dielectric, optical, and other properties in condensed matter
Statistical physics and thermodynamics

Electronic Nematic Ordering Driven by Atomicscale Multipoles
2021513
Theoretical investigations have unearthed a plethora of electronic nematic orderings driven by the spatial distribution of atomicscale electric quadrupoles.
Magnetic properties in condensed matter
Dielectric, optical, and other properties in condensed matter
Statistical physics and thermodynamics

A Solvent Viscositydependent Thermoelectric Conversion Efficiency
2021426
We found a beautiful empirical rule (α ∝ η^{0.4}) between the electrochemical Seebeck coefficient α for Fe^{2+}/Fe^{3+} redox pair and viscosity coefficient η of the organic solvent.
Structure and mechanical and thermal properties in condensed matter

Nanospaceconfined Helium Shows Fourdimensional Quantum Phase Transition (QPT)
2021419
Helium confined in a nanoporous material shows a four dimensional superfluid transition. This is a unique example of four dimensional critical phenomenon caused by strong quantum fluctuation.
Structure and mechanical and thermal properties in condensed matter

BKT Phase Transitions in Magnetic Systems: Formations of Narrow Stripes and Vortex–Antivortex Pairs in a Quasi2D Ferromagnet K_{2}CuF_{4}
2021414
Cryogenic Lorentz transmission electron microscopy directly shows that vortex and antivortex pairs emerge in a quasitwodimensional ferromagnet K_{2}CuF_{4}. This work may reveal the nature of Berezinskii, Kosterlitz, and Thouless phase transition in a magnetic system.
Magnetic properties in condensed matter
Structure and mechanical and thermal properties in condensed matter
Crossdisciplinary physics and related areas of science and technology

Simulating Equilibrium Behavior of Quantum Fields with Timeevolving Classical Fields
202145
A set of field configurations (replicas) reaches equilibrium of quantum field theory after realtime evolution obeying classical equations of motion.
Elementary particles, fields, and strings

Singlecrystal NaAlSi Shows Unconventional Superconductivity
2021329
Interesting normal and superconducting states of NaAlSi, a topological nodal line semimetal, were revealed by the measurements using the single crystals grown by the selfflux method.
Superconductivity

Phase Transition and Its Universality Class for a Quantum Spin Chain
2021329
We numerically diagonalize the DimerTrimer (DT) model Hamiltonian around the SU(3) symmetric point. As a result, we discover the phase transition at this point which belongs to the BerezinskiiKosterlitzThouless (BKT)like universality class.
Statistical physics and thermodynamics
Magnetic properties in condensed matter

Splitting Walls: Interplay of Different Orders in Multiferroic Materials
2021329
We theoretically showed an intrinsic splitting instability of composite domain walls in multiferroic materials under field drive. This instability is a direct result of the coexistence of multiple orders in the system.
Magnetic properties in condensed matter
Statistical physics and thermodynamics

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Random Numbers Can Help Solve Difficult Problems in Manybody Physics
2021329
Theorists review a random state vectorbased description of quantum manybody 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

A New Approach to Solving Periodic Differential Systems
2021329
Mathematicians and physicists are well acquainted with secondorder ordinary differential equations (ODE), the most prominent of them being the class of equations that govern oscillatory motion.
Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling

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Hybrid Quantum–Classical Algorithms: At the Verge of Useful Quantum Computing
2021322
Scientists discuss the recent progress in algorithms that have enabled hybrid quantum–classical computers, which has brought the quest to realize useful quantum computing much closer to its finish line.
Mathematical methods, classical and quantum physics, relativity, gravitation, numerical simulation, computational modeling
Crossdisciplinary physics and related areas of science and technology

Quantum Phase Transition in Spin Dimer Systems
2021322
A magnetic moment fluctuates in both longitudinal and transverse directions. The total moment sum rule is a conservation law that can help us resolve data of neutron scattering into the two components.
Magnetic properties in condensed matter

No Mass Gap Phase Transition in Novel Massless Dirac Fermion Material
2021322
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

Of Spins and Atoms: Combining Rotations to Obtain Directed Motion
2021322
The coupling between surface acoustic waves and spin waves is shown to depend strongly on the angle between the acoustic wavevector and magnetization. For a particular angle, it completely vanishes in one direction, which enables a unidirectional generation of surface acoustic waves by a ferromagnetic resonance.
Magnetic properties in condensed matter
Electromagnetism, optics, acoustics, heat transfer, and classical and fluid mechanics

Reducing the Number of Tests Using Bayesian Inference to Identify Infected Patients in Group Testing
2021322
Group testing is a method of identifying infected patients by performing tests on a pool of specimens. Bayesian inference and a corresponding belief propagation (BP) algorithm are introduced to identify the infected patients in group testing.
Statistical physics and thermodynamics
Crossdisciplinary physics and related areas of science and technology

Exploring the Pseudogap in Cuprate Superconductors
2021322
Electronic nematic correlation, in which electronic degree of freedom breaks the crystal symmetry, was found to have a potential link to the origin of hightemperature superconductivity in cooper oxide materials.
Superconductivity

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Antimatter Matters: Making Sense of the Matter–Antimatter Asymmetry at Japan’s BelleII Facility
2021322
Scientists embark on a quest to unravel the mysteries behind matter–antimatter asymmetry in our universe with the new BelleII experiment at the SuperKEKB accelerator in Japan.
Elementary particles, fields, and strings