Ken-Ichiro IMURA
Assistant Professor, Department of Quantum Matter, AdSM, Hiroshima University- Topics of Research：
- (D01) Theory of Topological Condensates
■ Laboratory Website
■ Description of Research
[161KB]
RESEARCH
Topological insulator (e.g., a quantum Hall state under a high magnetic field) has a seemingly "counterintuitive" property of being insulating in the bulk, but metallic on its surface. Its Z2 version, the Z2 topological insulator realizes such situation without magnetic field, i.e., without breaking time-reversal symmetry. I have been working on and uncovering various unexpected properties of this Z2 topological insulator, e.g., its robustness against disorder, its transport characteristics at the interface, the spectrum and localizability of its gapless surface states, etc. In this project I will partly focus on a new variation of such a Z2 topological insulator, often called a "topological Anderson insulator". A topological insulator by default means a topological band insulator. However, it has been pointed out recently that a trivial band insulator turns to a topological insulator solely by the effects of disorder. Another direction in which I plan to explore in this project is the study is of topological defects (e.g. crystalline dislocations) in topological insulators. A topological insulator under the influence of such topological defects seems to show topological signatures distinct from a topological insulator without topological defects. Characterization of such topological defects is also in the scope of this project.
EDUCATION
- 1995
- B.Sc. University of Tokyo, Department of Physics
- 1997
- M.S. University of Tokyo, Department of Applied Physics
- 1999
- Ph.D. University of Tokyo, Department of Applied Physics
PROFESSIONAL EXPERIENCE
- 1999-2000
- Laboratoire de Physique Theorique et des Models Statistique (LPTMS), Universite Paris XI, Orsay, France
- 2000-2002
- Laboratoire de Physique des Solides (LPS), Universite Paris XI, Orsay, France
- 2002-2003
- Institut fur Theoretische Festkorperphysik (TFP), Universitat Karlsruhe, Germany
- 2004-2007
- Condensed Matter Theory Laboratory, RIKEN
- 2007-2008
- Institute for Solid State Physics (ISSP), University of Tokyo
- 2008-2010
- Assistant Professor, Department of Physics, Tohoku University
- 2010-Present
- Assistant Professor, Department of Quantum Matter, AdSM, Hiroshima University
SELECTION OF PUBLICATIONS
"Finite-size energy gap in weak and strong topological insulators",
K.-I. Imura, M. Okamoto, Y. Yoshimura, Y. Takane, T. Ohtsuki,
Physical Review B 86, 245436-1-15 (Dec. 2012).
"Spherical topological insulator",
K.-I. Imura, Y. Yoshimura, Y. Takane, T. Fukui,
Physical Review B 86, 235119-1-12 (Dec. 2012).
"Spin Berry phase in the Fermi-arc states",
K.-I. Imura, Y. Takane,
Physical Review B 84, 245415-1-9 (Dec. 2011).
"Spin Berry phase in anisotropic topological insulators",
K.-I. Imura, Y. Takane, A. Tanaka,
Physical Review B 84, 195406-1-8 (Nov. 2011).
"Weak topological insulator with protected gapless helical states",
K.-I. Imura, Y. Takane, A.Tanaka,
Physical Review B 84, 035443-1-8 (Jul. 2011).
"Disorder-Induced Multiple Transition involving Z2 Topological Insulator",
Ai Yamakage, Kentaro Nomura,K.-I. Imura and Yoshio Kuramoto,
J. Phys. Soc. Jpn. 80, 053703 (2011).
"Josephson Current through a Planar Junction of Graphene",
Yositake Takane and K.-I. Imura,
J. Phys. Soc. Jpn. 80, 043702 (2011).
"Interfacial charge and spin transport in Z2 topological insulators",
A. Yamakage, K.-I. Imura, J. Cayssol and Y. Kuramoto,
Phys. Rev. B 83, 125401 (2011).
"Analytic Theory of Edge Modes in Topological Insulators",
Shijun Mao, Yoshio Kuramoto,K.-I. Imura and Ai Yamakage,
J. Phys. Soc. Jpn. 79, 124709 (2010).
"Zigzag edge modes in a Z2 topological insulator: Reentrance and completely flat spectrum",
K.-I. Imura, Ai Yamakage, Shijun Mao, Akira Hotta and Yoshio Kuramoto,
Phys. Rev. B 82, 085118 (2010).
"Anti-localization of graphene under the substrate electric field",
K.-I. Imura, Y. Kuramoto and Ken Nomura,
Europhys. Lett. 89, 17009 (2010).
"Spin-orbit effects in a graphene bipolar pn junction",
A. Yamakage, K.-I. Imura, J. Cayssol, Y. Kuramoto,
Europhys. Lett. 87, 47005 (2009).
"Weak localization properties of doped Z2 topological insulator",
K.-I. Imura, Yoshio Kuramoto, Kentaro Nomura,
Phys. Rev. B 80, 085119 (2009).
"Colossal spin fluctuations in a molecular quantum dot magnet with ferromagnetic electrodes",
T. Jonckheere, K.-I. Imura and Th. Martin,
Phys. Rev. B 78, 045316 (2008).
"Quantum Hall effect in bilayer and multilayer graphene with finite Fermi energy",
M. Nakamura, L. Hirasawa and K.-I. Imura,
Phys. Rev. B 78, 033403 (2008).
"Numerical study of transport through a single impurity in a spinful Tomonaga-Luttinger liquid",
Y. Hamamoto, K.-I. Imura and T. Kato,
Phys. Rev. B 77, 165402 (2008).
"Full counting statistics for transport through a molecular quantum dot magnet",
K.-I. Imura, Y. Utsumi, Th. Martin,
Phys. Rev. B 75, 205341 (2007).
