A5029751621- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Advanced Condensed Matter Physics
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- Graphene research and applications
- Electronic and Structural Properties of Oxides
- Multiferroics and related materials
- Theoretical and Computational Physics
- Rare-earth and actinide compounds
- Quantum many-body systems
- Cold Atom Physics and Bose-Einstein Condensates
- 2D Materials and Applications
- Superconducting Materials and Applications
- Quantum, superfluid, helium dynamics
- Organic and Molecular Conductors Research
- Advanced Chemical Physics Studies
- Iron-based superconductors research
- Semiconductor Quantum Structures and Devices
- Solid-state spectroscopy and crystallography
- Superconductivity in MgB2 and Alloys
- Spectroscopy and Quantum Chemical Studies
- Surface and Thin Film Phenomena
- Mechanical and Optical Resonators
RIKEN Center for Emergent Matter Science
2016-2025
RIKEN
2008-2025
The University of Tokyo
2015-2024
Quantum Chemistry Research Institute
2024
Bunkyo University
2023
Institute for Basic Science
2017
Seoul National University
2017
RIKEN Advanced Science Institute
2009-2015
Lattice Semiconductor (United States)
2011
National Institute of Advanced Industrial Science and Technology
2002-2009
This article reviews the physics of high-temperature superconductors from point view doping a Mott insulator. The basic electronic structure cuprates is reviewed, emphasizing strong correlation and establishing model doped insulator as starting point. A variety experiments are discussed, focusing on region phase diagram close to (the underdoped region) where behavior most anomalous. normal state in this exhibits pseudogap phenomenon. In contrast, quasiparticles superconducting well defined...
We present a review of experimental and theoretical studies the anomalous Hall effect (AHE), focusing on recent developments that have provided more complete framework for understanding this subtle phenomenon have, in many instances, replaced controversy by clarity. Synergy between work, both playing crucial role, has been at heart these advances. On front, adoption Berry-phase concepts established link AHE topological nature currents which originate from spin-orbit coupling. new transition...
An electron in a solid, that is, bound to or nearly localized on the specific atomic site, has three attributes: charge, spin, and orbital. The orbital represents shape of cloud solid. In transition-metal oxides with anisotropic-shaped d-orbital electrons, Coulomb interaction between electrons (strong correlation effect) is importance for understanding their metal-insulator transitions properties such as high-temperature superconductivity colossal magnetoresistance. degree freedom...
A new mechanism of the magnetoelectric effect based on spin supercurrent is theoretically presented in terms a microscopic electronic model for noncollinear magnets. The electric polarization P(ij) produced between two magnetic moments S(i) and S(j) given by P proportional e(ij) X (S(i) S(j)) with being unit vector connecting sites i j. Applications to spiral structure gauge theoretical interpretation are discussed.
Although microscopic laws of physics are invariant under the reversal arrow time, transport energy and information in most devices is an irreversible process. It this irreversibility that leads to intrinsic dissipations electronic limits possibility quantum computation. We theoretically predict electric field can induce a substantial amount dissipationless spin current at room temperature, hole-doped semiconductors such as Si, Ge, GaAs. On basis generalization Hall effect, predicted effect...
We derive the semiclassical equation of motion for wave packet light taking into account Berry curvature in momentum-space. This naturally describes interplay between orbital and spin angular momenta, i.e., conservation total momentum light. leads to shift wave-packet perpendicular gradient dielectric constant, polarization-dependent Hall effect An enhancement this photonic crystals is also proposed.
Efforts to find the magnetic monopole in real space have been made cosmic rays and particle accelerators, but there has not yet any firm evidence for its existence because of very heavy mass, approximately 10(16) giga-electron volts. We show that can appear crystal momentum solids accessible low-energy region (approximately 0.1 1 electron volts) context anomalous Hall effect. report experimental results together with first-principles calculations on ferromagnetic SrRuO3 provide space.
Multiferroics, compounds with both magnetic and ferroelectric orders, are believed to be a key material system achieve cross-control between magnetism electricity in solid minute energy dissipation. Such colossal magnetoelectric (ME) effect has been an issue of keen interest for long time condensed matter physics as well most desired function the emerging spin-related electronics. Here we begin basic mechanisms realize multiferroicity or spin-driven ferroelectricity materials, which have...
An electron hopping on non-coplanar spin sites with chirality obtains a complex phase factor (Berry phase) in its quantum mechanical amplitude that acts as an internal magnetic field, and is predicted to manifest itself the Hall effect when it not cancelled. The present combined work of transport measurement, neutron scattering, theoretical calculation provides evidence gigantic anomalous observed Nd2Mo2O7, pyrochlore ferromagnet geometrically frustrated lattice structure, mostly due...
The Hall effect usually occurs when the Lorentz force acts on a charge current in conductor presence of perpendicular magnetic field. On other hand, neutral quasi-particles such as phonons and spins can carry heat potentially show without resorting to force. We report experimental evidence for anomalous thermal caused by spin excitations (magnons) an insulating ferromagnet with pyrochlore lattice structure. Our theoretical analysis indicates that propagation wave is influenced...
We study a version of the uniform resonating-valence-band state in which fermions and spinless bosons are coupled by gauge field. show that above Bose-Einstein temperature, boson inverse lifetime due to scattering field is order kT, suppresses condensation temperature leads linear T resistivity. The Hall number proportional hole density dependent. single-particle spectral weight exhibits continuum plus broadened peak. ``Fermi surface'' area satisfies Luttinger's theorem. Comparison with...
Starting with the one-band t-J model and using slave-boson method to enforce constraint of no double occupations, we examine fluctuations about uniform resonating-valence-bond mean-field solution. We restrict our attention a temperature region where bosons are not Bose condensed. The important low-energy described by gauge fields that related in spin chirality. fermions strongly coupled field, leading transport time order \ensuremath{\Elzxh}/${\mathit{k}}_{\mathit{B}}$T, agreement...
A ferromagnet with spin anisotropies on the 2D Kagome lattice is theoretically studied. This a typical example of flat-band ferromagnet. The Berry phase induced by tilting spins opens band gap and quantized Hall conductance \sigma_{xy}=\pm e^2/h realized without external magnetic field. most realistic chiral state based ferromagnetism. We also discuss implication our results to anomalous effect observed in metallic pyrochlore ferromagnets R_2Mo_2O_7(R=Nd, Sm, Gd).
Superconductivity is a phenomenon where the macroscopic quantum coherence appears due to pairing of electrons. This offers fascinating arena study physics broken gauge symmetry. However, important symmetries in superconductors are not only invariance. Especially, symmetry properties pairing, i.e., parity and spin-singlet/spin-triplet, determine physical superconducting state. Recently it has been recognized that there third pair amplitude, even or odd with respect frequency. The conventional...
The anomalous Hall effect (AHE) and Nernst (ANE) are experimentally investigated in a variety of ferromagnetic metals including pure transition metals, oxides, chalcogenides, whose resistivities range over 5 orders magnitude. For these ferromagnets, the transverse conductivity ${\ensuremath{\sigma}}_{xy}$ versus longitudinal ${\ensuremath{\sigma}}_{xx}$ shows crossover behavior with three distinct regimes accordance qualitatively recent unified theory intrinsic extrinsic AHE. We also found...
We study theoretically the transport properties of a normal metal (N)/ferromagnet insulator (FI)/superconductor (S) junction and S/FI/S formed on surface three-dimensional topological insulator, where chiral Majorana mode exists at FI/S interface. find generated in N/FI/S junctions is very sensitively controlled by direction magnetization m FI region. In particular, current-phase relation Josephson current has phase shift neither 0 nor pi that can be tuned continuously component perpendicular to