991 citations · 1.9k across the 29 of their papers we have counts for
29 papers
Formulation of the orbital magnetic moment in multiorbital tight-binding models: Application to the inverse Faraday effect
Kosuke Tazuke, Takahiro Morimoto, Sota Kitamura
We establish a theoretical formulation of the orbital magnetic moment in multiorbital tight-binding models, focusing on the role of the electric dipole. We demonstrate that the tot…
Quantum Optical Spanner: Twisting Superconductors with Vortex Beam via Higgs Mode
Daemo Kang, Sota Kitamura, Takahiro Morimoto
Light carrying orbital angular momentum (OAM)--known as vortex beams--has broadened the scope of understanding and applications of light's angular momentum. Optical tweezers using…
Dirac Electrons in AC-Magnetic Fields: -Landau Levels and Chiral Anomaly-Induced Homodyne Effect
Sota Kitamura, Takashi Oka
Floquet engineering, which involves controlling systems through time-periodic driving, is a method for coherently manipulating quantum materials and realizing dynamical states with…
Controllable photocurrent generation in Dirac systems with two frequency drives
Yuya Ikeda, Sota Kitamura, Takahiro Morimoto
We study the bulk photovoltaic effect (BPVE) in Dirac and Weyl semimetals under two-frequency light irradiation. We show that the BPVE emerges for centrosymmetric Dirac and Weyl se…
Unexpected linear conductivity in Landau-Zener model: limitations and improvements of the relaxation time approximation in the quantum master equation
Ibuki Terada, Sota Kitamura, Hiroshi Watanabe +1
The nonequilibrium steady states of quantum materials have many challenges. Here, we highlight issues with the relaxation time approximation (RTA) for the DC conductivity in insula…
Brillouin zone folding method for quasiperiodic superconductivity in multilayer systems: application to electronic structure and optical responses
Mao Yoshii, Sota Kitamura, Takahiro Morimoto
We construct an efficient momentum space approach to the superconductivity in quasiperiodic multilayer systems. To this end, we extend the Brillouin zone (BZ) folding method to the…
Time-dependent Gutzwiller simulation of Floquet topological superconductivity
Takahiro Anan, Takahiro Morimoto, Sota Kitamura
Periodically driven systems provide a novel route to control the topology of quantum materials. In particular, Floquet theory allows an effective band description of periodically-d…
Geometric aspects of nonlinear and nonequilibrium phenomena
Takahiro Morimoto, Sota Kitamura, Naoto Nagaosa
We review recent developments in the research of nonlinear and nonequilibrium phenomena in solids focusing on their geometrical aspects. We start with introducing the basic concept…
Photocurrent induced by a bicircular light drive in centrosymmetric systems
Yuya Ikeda, Sota Kitamura, Takahiro Morimoto
A bicircular light (BCL) consists of left and right circularly polarized lights with different frequencies, and draws a rose-like pattern with a rotational symmetry determined by t…
Gap labeling theorem for multilayer thin film heterostructures
Mao Yoshii, Sota Kitamura, Takahiro Morimoto
Quasiperiodic systems show a universal gap structure due to quasiperiodicity which is analogous to gap openings at the Brillouin zone boundary in periodic systems. The integrated d…
Nonlinear spin current of photoexcited magnons in collinear antiferromagnets
Kosuke Fujiwara, Sota Kitamura, Takahiro Morimoto
We study the nonlinear magnon spin current induced by an ac electric field under light irradiation in collinear antiferromagnets with broken inversion symmetry. For linearly polari…
Thermal Hall responses in frustrated honeycomb spin systems
Kosuke Fujiwara, Sota Kitamura, Takahiro Morimoto
We study geometrical responses of magnons driven by a temperature gradient in frustrated spin systems. While Dzyaloshinskii-Moriya (DM) interactions are usually incorporated to obt…
Optical response of the Leggett mode in multiband superconductors in the linear response regime
Takumi Kamatani, Sota Kitamura, Naoto Tsuji +2
We study optical responses of Leggett modes in multiband superconductors in the linear response regime. The Leggett mode is a collective mode unique to multiband superconductors th…
Floquet topological superconductivity induced by chiral many-body interactions
Sota Kitamura, Hideo Aoki
We study how a -wave superconductivity is changed when illuminated by circularly-polarised light (CPL) in the repulsive Hubbard model in the strong-coupling regime. We adopt the…
Floquet engineering of electric polarization with two-frequency drive
Yuya Ikeda, Sota Kitamura, Takahiro Morimoto
Electric polarization is a geometric phenomenon in solids and has a close relationship to the symmetry of the system. Here we propose a mechanism to dynamically induce and manipula…
Topological charge pumping in quasiperiodic systems characterized by Bott index
Mao Yoshii, Sota Kitamura, Takahiro Morimoto
We study topological charge pumping in one-dimensional quasiperiodic systems. Since these systems lack periodicity, we cannot use the conventional approach based on the topological…
Electric polarization and nonlinear optical effects in noncentrosymmetric magnets
Takahiro Morimoto, Sota Kitamura, Shun Okumura
We study electric polarization and nonlinear optical effects in spin systems with broken inversion symmetry. We apply strong coupling expansion to the underlying electronic Hamilto…
Current response of nonequilibrium steady states in Landau-Zener problem: Nonequilibrium Green's function approach
Sota Kitamura, Naoto Nagaosa, Takahiro Morimoto
The carrier generation in insulators subjected to strong electric fields is characterized by the Landau-Zener formula for the tunneling probability with a nonperturbative exponent.…
Nonreciprocal Landau-Zener tunneling
Sota Kitamura, Naoto Nagaosa, Takahiro Morimoto
Application of strong dc electric field to an insulator leads to quantum tunneling of electrons from the valence band to the conduction band, which is a famous nonlinear response k…
Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO
Hidetomo Usui, Masayuki Ochi, Sota Kitamura +8
We study the electronic structure of delafossite PtCoO to elucidate its extremely small resistivity and high mobility. The band exhibits steep dispersion near the Fermi level d…
Spin Hall effect in 2D metallic delafossite PtCoO and vicinity topology
Sota Kitamura, Hidetomo Usui, Robert-Jan Slager +9
The two-dimensional (2D) metal PtCoO is renowned for the lowest room temperature resistivity among all oxides, close to that of the top two materials Ag and Cu. In addition, we…
Probing spin correlations using angle resolved photoemission in a coupled metallic/Mott insulator system
V. Sunko, F. Mazzola, S. Kitamura +16
A nearly free electron metal and a Mott insulating state can be thought of as opposite ends of possibilities for the motion of electrons in a solid. In the magnetic oxide metal PdC…
Floquet Engineering of Quantum Materials
Takashi Oka, Sota Kitamura
Floquet engineering, the control of quantum systems using periodic driving, is an old concept in condensed matter physics, dating back to ideas such as the inverse Faraday effect.…
Probing and controlling spin chirality in Mott insulators by circularly polarized laser
Sota Kitamura, Takashi Oka, Hideo Aoki
Scalar spin chirality, a three-body spin correlation that breaks time-reversal symmetry, is revealed to couple directly to circularly polarized laser. This is shown by the Floquet…