80 citations · 251 across the 7 of their papers we have counts for
9 papers
Edge states in graphene in magnetic fields -- a speciality of the edge mode embedded in the n=0 Landau band
Mitsuhiro Arikawa, Yasuhiro Hatsugai, Hideo Aoki
While usual edge states in the quantum Hall effect(QHE) reside between adjacent Landau levels, QHE in graphene has a peculiar edge mode at E=0 that reside right within the n=0 Land…
Degeneracy and Consistency Condition of Berry phases: Gap Closing under the Twist
Takaaki Hirano, Hosho Katsura, Yasuhiro Hatsugai
We have discussed a consistency condition of Berry phases defined by a local gauge twist and spatial symmetries of the many body system. It imposes a non trivial gap closing condit…
Topological Aspects of Surface States in Semiconductors
Yoshihiro Kuge, Isao Maruyama, Yasuhiro Hatsugai
Topological aspects of surface states in semiconductors are studied by an adiabatic deformation which connects a realistic system and a decoupled covalent-bond model. Two topologic…
Topological Classification of Gapped Spin Chains :Quantized Berry Phase as a Local Order Parameter
Takaaki Hirano, Hosho Katsura, Yasuhiro Hatsugai
We characterize several phases of gapped spin systems by local order parameters defined by quantized Berry phases. This characterization is topologically stable against any small p…
Charge and spin stripe in LaSrNiO (x=1/3,1/2)
S. Yamamoto, T. Fujiwara, Y. Hatsugai
Electronic structure of stripe ordered LaSrNiO is investigated. The system with x=1/3 is insulator, in LSDA+U calculations, and shows charge and spin stripe, co…
Entanglement Entropy of One-dimensional Gapped Spin Chains
Takaaki Hirano, Yasuhiro Hatsugai
We investigate the entanglement entropy (EE) of gapped S=1 and spin chains with dimerization. We find that the effective boundary degrees of freedom as edge states contribu…