Masashi Shiraishi: Difference between revisions

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==Affiliation==
==Affiliation==
* Department of Electronic Science and Engineering, Kyoto Univ., Japan.
* Department of Electronic Science and Engineering, Kyoto University, Japan


==Title==
==Title==
Line 6: Line 6:


==Abstract==
==Abstract==
Topological insulator (TI) is a new class of a condensed matter, where a bulk state is
Topological insulator (TI) is a new class of a condensed matter, where a bulk state is insulating and a surface (or an edge) state has the Dirac-­like linear band structure. The surface state is topologically protected due to existence of the Chern­-Simons term and the gauge invariance conservation. In consequence, the state is in principle 100% spin polarized, i.e., a persistent pure spin current exists due to a so­-called spin­-momentum locking. Thus, much effort has been paid for its detection. Angle ­resolved photoemission spectroscopy has been the most potential method for the detection, but recently, an electrical method enables to detect the surface spin polarization. Here we introduce the detection of the surface spin polarization of a TI, BiSbTeSe(BSTS) [1], which is the first bulk insulating TI. In this study, a local 3-terminal method allows to detect the spin­-momentum locking in BSTS, and the spin accumulation beneath a ferromagnetic electrode was successfully detected up to 125 K. The detail of the experiments and discussion will be discussed in the presentation. Furthermore, we briefly show transport properties of the first hole carrier TI, TlBiSe [2], if time permits.


insulating and a surface (or an edge) state has the Dirac­like linear band structure. The
==Collaborators==
 
* Yoichi Ando, University of Koern, Germany
surface state is topologically protected due to existence of the Chern­Simons term and
* Akio Kimura, Hiroshima University, Japan
 
* Yuichiro Ando, Kyoto University, Japan
the Gauge invariance conservation. In consequence, the state is in principle 100% spin
* Gaku Eguchi, Kyoto University, Japan
 
polarized, i.e., a persistent pure spin current exists due to a so­called spin­momentum
 
locking. Thus, much effort has been paid for its detection. Angle­resolved photoemission
 
spectroscopy has been the most potential method for the detection, but recently, an
 
electrical method enables to detect the surface spin polarization.
 
Here we introduce the detection of the surface spin polarization of a TI,
 
BiSbTeSe(BSTS) [1], which is the first bulk insulating TI. In this study, a local 3­terminal
 
method allows to detect the spin­momentum locking in BSTS, and the spin accumulation
 
beneath a ferromagnetic electrode was successfully detected up to 125 K. The detail of
 
the experiments and discussion will be discussed in the presentation. Furthermore, we
 
briefly show transport properties of the first hole carrier TI, TlBiSe [2], if time permits.
 
These studies were implemented by collaboration with Prof. Yoichi Ando (Univ. Koern,
 
Germany), Prof. Akio Kimura (Hiroshima Univ., Japan), Dr. Yuichiro Ando and Dr. Gaku
 
Eguchi (Kyoto University, Japan).


==References==
==References==


* [1] Yuichiro Ando, Yoichi Ando, Masashi Shiraishi et al., Nano Letters 14, 6226 (2014).
* [1] Y. Ando, T. Hamasaki, T. Kurokawa, K. Ichiba, F. Yang, M. Novak, S. Sasaki, K. Segawa, Y. Ando, and M. Shiraishi, ''Electrical detection of the spin polarization due to charge flow in the surface state of the topological insulator Bi<sub>1.5</sub>Sb<sub>0.5</sub>Te<sub>1.7</sub>Se<sub>1.3</sub>'', [http://pubs.acs.org/doi/abs/10.1021/nl502546c Nano Lett. '''14''', 6226 (2014)].
 
* [2] Gaku Eguchi, Akio Kimura, Masashi Shiraishi et al., Physical Review B90, 201307(R),


2014.
* [2] G. Eguchi, K. Kuroda, K. Shirai, A. Kimura, and M. Shiraishi, ''Surface Shubnikov–de Haas oscillations and nonzero Berry phases of the topological hole conduction in Tl<sub>1−x</sub>Bi<sub>1+x</sub>Se<sub>2</sub>, Phys. Rev. B '''90''', 201307(R) (2014).

Revision as of 10:28, 13 August 2015

Affiliation

  • Department of Electronic Science and Engineering, Kyoto University, Japan

Title

Electrical detection of surface spin polarization due to spin­-momentum locking in BiSbTeSe

Abstract

Topological insulator (TI) is a new class of a condensed matter, where a bulk state is insulating and a surface (or an edge) state has the Dirac-­like linear band structure. The surface state is topologically protected due to existence of the Chern­-Simons term and the gauge invariance conservation. In consequence, the state is in principle 100% spin polarized, i.e., a persistent pure spin current exists due to a so­-called spin­-momentum locking. Thus, much effort has been paid for its detection. Angle ­resolved photoemission spectroscopy has been the most potential method for the detection, but recently, an electrical method enables to detect the surface spin polarization. Here we introduce the detection of the surface spin polarization of a TI, BiSbTeSe(BSTS) [1], which is the first bulk insulating TI. In this study, a local 3-terminal method allows to detect the spin­-momentum locking in BSTS, and the spin accumulation beneath a ferromagnetic electrode was successfully detected up to 125 K. The detail of the experiments and discussion will be discussed in the presentation. Furthermore, we briefly show transport properties of the first hole carrier TI, TlBiSe [2], if time permits.

Collaborators

  • Yoichi Ando, University of Koern, Germany
  • Akio Kimura, Hiroshima University, Japan
  • Yuichiro Ando, Kyoto University, Japan
  • Gaku Eguchi, Kyoto University, Japan

References

  • [1] Y. Ando, T. Hamasaki, T. Kurokawa, K. Ichiba, F. Yang, M. Novak, S. Sasaki, K. Segawa, Y. Ando, and M. Shiraishi, Electrical detection of the spin polarization due to charge flow in the surface state of the topological insulator Bi1.5Sb0.5Te1.7Se1.3, Nano Lett. 14, 6226 (2014).
  • [2] G. Eguchi, K. Kuroda, K. Shirai, A. Kimura, and M. Shiraishi, Surface Shubnikov–de Haas oscillations and nonzero Berry phases of the topological hole conduction in Tl1−xBi1+xSe2, Phys. Rev. B 90, 201307(R) (2014).