79 citations · 418 across the 26 of their papers we have counts for
26 papers
Observation of g-wave altermagnetic multipole
Ryo Misawa, Rikuto Oiwa, Shunsuke Kitou +16
Over the past few years, altermagnets have emerged as a new class of collinear magnets with broken time-reversal symmetry, offering novel opportunities for spintronics beyond conve…
Sixteenfold Classification of Many-Body Multipoles from Rotation-Compatible Canonical Symmetries
Shingo Kuniyoshi, Rikuto Oiwa, Satoru Hayami
The conventional multipole framework provides a standard symmetry-based language for one-body electronic degrees of freedom, but fails to distinguish physically distinct sectors in…
Piezoaxial coupling for strain-selected ferroaxial domain control
Rikuto Oiwa, Satoru Hayami
We formulate a symmetry-based hierarchy of strain-derived conjugate fields for ferroaxial order, and demonstrate strain-selected ferroaxial domain control using first-principles ca…
Circular Raman responses from angular-momentum inequivalence in CoSi
Yuki Suganuma, Gakuto Kusuno, Kohei Miyazaki +8
Circularly polarized Raman scattering in solids exhibits distinct phenomena such as Raman optical activity (ROA) and chiral-phonon-induced frequency splitting, whose relationship h…
Effective phonon models based on symmetry-adapted multipole basis -- Hidden chiral phonon angular momentum splitting in ferroaxial systems
Yu Xie, Rikuto Oiwa, Satoru Hayami
We propose a symmetry-based framework for constructing effective harmonic phonon models using a symmetry-adapted multipole basis. By decomposing the force-constant matrix into bond…
Electric toroidal octupolar symmetry in pyrite FeS probed by Raman optical activity
Yuki Suganuma, Gakuto Kusuno, Hikaru Watanabe +4
We report Raman optical activity in pyrite FeS, which hosts an electric toroidal octupolar symmetry. A clear and reproducible sign reversal of the circular intensity difference…
Theory of Many-Body Multipole Operators in Single-Centered Electron Systems: Two-Body Toroidal Monopoles in Spinless Orbitals
Shingo Kuniyoshi, Rikuto Oiwa, Satoru Hayami
One-body multipole operators are defined as irreducible representations of rotational symmetry together with spatial-inversion and time-reversal symmetries, providing a systematic…
Large magneto-optical Kerr effect induced by collinear antiferromagnetic order
H. Yoshimochi, K. Yoshida, R. Oiwa +6
In modern technology, the optical readout of magnetic information is conventionally achieved by the magneto-optical Kerr effect, i.e., the polarization rotation of reflected light.…
Spinless electric toroidal multipoles in ferroaxial revealed by symmetry-adapted closest Wannier analysis
Yu Xie, Rikuto Oiwa, Satoru Hayami
From a symmetry perspective, ferroaxial order belongs to the same symmetry as time-reversal-even pseudovectors. Experimentally, is known to undergo a displaci…
Chirality/Axiality-Induced Axiality/Chirality via Surface Polarization
Satoru Hayami, Rikuto Oiwa, Akane Inda
In condensed matter physics, a broad spectrum of physical characteristics, such as chirality, axiality, and polarity, arises as a direct consequence of the underlying symmetry of t…
Detection of ferroic octupole ordering in -wave altermagnetic rutile-type compounds
Masaichiro Mizumaki, Norimasa Sasabe, Takayuki Uozumi +2
We propose that X-ray absorption and emission magnetic circular dichroism (XAS-MCD and XES-MCD) are promising measurements to directly detect ferroic higher-rank multipoles as cand…
Dual-circular Raman optical activity of axial multipolar order
Hikaru Watanabe, Rikuto Oiwa, Hitoshi Mori +1
Multipolar order, such as octupolar order, is a key concept in condensed matter physics, particularly in light of elusive hidden orders. However, its experimental identification re…
Symmetry analysis of cross-circular and parallel-circular Raman optical activity
Hikaru Watanabe, Rikuto Oiwa, Gakuto Kusuno +2
The Raman scattering regarding the circularly-polarized incident and scattered lights is closely related to the circular activity of a given system. We investigate the symmetry of…
Raman Optical Activity Induced by Ferroaxial Order in NiTiO
Gakuto Kusuno, Takeshi Hayashida, Takayuki Nagai +4
Raman optical activity (ROA), the dependence of Raman intensity on the circular polarization of incident and scattered light, has traditionally been observed in chiral molecules an…
Predominant Electronic Order Parameter for Structural Chirality -- Role of Spinless Electronic Toroidal Multipoles
Rikuto Oiwa, Hiroaki Kusunose
We discuss predominant order parameters for structural chirality, and demonstrate that time-reversal-even axial-quadrupole plays a key role in stabilizing a chiral structure. Using…
Symmetry-adapted closest Wannier modeling based on complete multipole basis set
Rikuto Oiwa, Akane Inda, Satoru Hayami +3
We have developed a method to construct a symmetry-adapted Wannier tight-binding model based on the closest Wannier formalism and the symmetry-adapted multipole theory. Since the s…
Quantification of chirality based on electric toroidal monopole
Akane Inda, Rikuto Oiwa, Satoru Hayami +2
Chirality ubiquitously appears in nature, however, its quantification remains obscure owing to the lack of microscopic description at the quantum-mechanical level. We propose a way…
Unconventional Hall effect and magnetoresistance induced by metallic ferroaxial ordering
Satoru Hayami, Rikuto Oiwa, Hiroaki Kusunose
Transport property under metallic ferroaxial ordering in an external magnetic field is theoretically investigated. After presenting the relation between the magnetoconductivity ten…
Symmetry-adapted modeling for molecules and crystals
Hiroaki Kusunose, Rikuto Oiwa, Satoru Hayami
We have developed a symmetry-adapted modeling procedure for molecules and crystals. By using the completeness of multipoles to express spatial and time-reversal parity-specific ani…
Rotation and electric-field responses and absolute enantioselection in chiral crystals
Rikuto Oiwa, Hiroaki Kusunose
Microscopic origin of chirality and possible electric-field induced rotation and rotation-field induced electric polarization are investigated. By building up a realistic tight-bin…
Electric Ferro-Axial Moment as Nanometric Rotator and Source of Longitudinal Spin Current
Satoru Hayami, Rikuto Oiwa, Hiroaki Kusunose
An electric ferro-axial moment, which is characterized by a nonzero expectation value of a time-reversal-even axial vector, exhibits distinct spatial-inversion and time-reversal pr…
Analysis of model parameter dependences on the second-order nonlinear conductivity in -symmetric collinear antiferromagnetic metals with magnetic toroidal moment on zigzag chains
Megumi Yatsushiro, Rikuto Oiwa, Hiroaki Kusunose +1
A magnetic toroidal moment is a fundamental electronic degree of freedom in the absence of both spatial inversion and time-reversal symmetries and gives rise to novel multiferroic…
Systematic analysis method for nonlinear response tensors
Rikuto Oiwa, Hiroaki Kusunose
We propose a systematic analysis method for identifying essential parameters in various linear and nonlinear response tensors without which they vanish. By using the Keldysh formal…
Complete Multipole Basis Set for Single-Centered Electron Systems
Hiroaki Kusunose, Rikuto Oiwa, Satoru Hayami
A whole series of expressions for four species of multipoles (electric, magnetic, magnetic toroidal, and electric toroidal) is provided as a complete basis set to describe arbitrar…