53 citations · 165 across the 6 of their papers we have counts for
6 papers
Direct Observation of the Quantum Phase Transition of SrCu(BO) by High-Pressure and Terahertz Electron Spin Resonance
Takahiro Sakurai, Yuki Hirao, Keigo Hijii +5
High-pressure and high-field electron spin resonance (ESR) measurements have been performed on a single crystal of the orthogonal-dimer spin system SrCu(BO). With…
Structure of energy level degeneracy of a single-spin model from a view point of symmetry of the spin anisotropy and its nontrivial spin()-dependence on the higher order anisotropy
Keigo Hijii, Seiji Miyashita
We study structure of the gapless points (diabolical points) at zero magnetic field () of single-spin models with spin anisotropies. Nontrivial appearance of diabolical poin…
Phase diagram of S=1/2 two-leg XXZ spin ladder systems
K. Hijii, A. Kitazawa, K. Nomura
We investigate the ground state phase diagram of the S=1/2 two-leg spin ladder system with an isotropic interchain coupling. In this model, there is the Berezinskii-Kosterlit…
Phase diagram of S=1 XXZ chain with next-nearest neighbor interaction
Takahiro Murashima, Keigo Hijii, Kiyohide Nomura +1
The one dimensional S=1 XXZ model with next-nearest-neighbor interaction and Ising-type anisotropy is studied by using a numerical diagonalization technique. We discuss the…
Staggered dimer order in S=1/2 quantum spin ladder system with four spin exchange
Keigo Hijii, Shaojin Qin, Kiyohide Nomura
We study the S=1/2 quantum spin ladder system with the four-spin exchange, using density matrix renormalization group method and an exact diagonalization method. Recently, the phas…
Universality class of S=1/2 quantum spin ladder system with the four spin exchange
Keigo Hijii, Kiyohide Nomura
We study s=1/2 Heisenberg spin ladder with the four spin exchange. Combining numerical results with the conformal field theory(CFT), we find a phase transition with central charge…