Introduction

Principal Scientist
Research Group for Spin-energy Science,
Advanced Science Research Center,
Japan Atomic Energy Agency,
Tokai, Ibaraki 319-1195, JAPAN
E-mail: onishi.hiroaki [-AT-] jaea.go.jp

I am a research scientist working on condensed matter theory. I am broadly interested in:

strongly correlated electron systems, quantum spin systems, and cold atoms in optical lattices
charge-spin-orbital-phonon degrees of freedom
geometrical frustration
magnetism
dynamics (spectroscopy, non-equilibrium phenomena, transport)
computational physics

More specifically, I have studied spin-orbital ordering and its dynamics in strongly correlated electron systems with orbital degeneracy, such as transition metal oxides, rare earth compounds, and actinide compounds. I have recently studied quantum spin magnetism in low dimensions. Particularly, I am currently focusing on dynamics and transport properties in quantum spin systems, such as spin nematics, envisaging possible applications in spintronics.

I have tackled these research subjects by exploiting various numerical methods, such as density-matrix renormalization group (DMRG), time-dependent DMRG, dynamical DMRG, Lanczos diagonalization, thermal pure quantum state, and quantum Monte Carlo loog algorithm. I have developed expertise in parallel computing using MPI and OpenMP.

Topics

Remarked Paper:

JPSJ Papers of Editors' Choice
"Magnetic Excitation in the S=1/2 Ising-like Antiferromagnetic Chain CsCoCl3 in Longitudinal Magnetic Fields Studied by High-field ESR Measurements"
Shojiro Kimura, Hiroaki Onishi, Kouichi Okunishi, Mitsuru Akaki, Yasuo Narumi, Masayuki Hagiwara, Koichi Kindo, and Hikomitsu Kikuchi
J. Phys. Soc. Jpn. 92, 094701 (2023).

JPSJ Papers of Editors' Choice
"Magnetic Excitations of Spin Nematic State in Frustrated Ferromagnetic Chain"
Hiroaki Onishi
J. Phys. Soc. Jpn. 84, 083702 (2015).