Nano Research & Applications

Spin-orbit interaction and topological phase in atom-thin layers

17^th Edition of International Conference on Emerging Trends in Materials Science and Nanotechnology
April 26-27, 2018 Rome, Italy

J Haruyama

Aoyama Gakuin University, Japan Institute for Solid State Physics - University of Tokyo, Japan

ScientificTracks Abstracts: Nano Res Appl

DOI: 10.21767/2471-9838-C1-008

Abstract

Three dimensional (3D) topological insulating (TI) state, in which the bulk is insulator with an energy band gap while the surface is gapless conductor, has been reported in some materials and attracted significant attention. On the other hand, 2D TI states have been experimentally reported only in few materials, such as quantum wells of HgTe/CdTe or InAs/ GaSb. In 2D TI state, quantum SHE (QSHE) is observed with a bulk energy gap but gapless helical edge states protected by time reversal symmetry, in which opposite spin states forming a Kramers doublet counter propagate. Although 2D TI states are theoretically predicted for graphene, atomically thin 2D carbon layer, experimental observation is rare. On the other hand, atom-thin transition metal dichalcogenide (TMDC) layers are attracting significant attention from various viewpoints. It has been recently predicted that 1T�-phase of such layers can be within 2D TI states due to the band inversion. Thus, it is indispensable to realize 2D and 1D TI states in various atomthin materials. For the creation of TI states, introduction of spin-orbit interactions (SOIs) is crucial. Recently, challenge of introduction of SOI into graphene has been experimentally reported by some methods [e.g., surface decoration by (1) rightmass adatoms or (2) heavy nanoparticles, and (3) using heavy substrates]. In the talk, I will present (1) and (2) using small amount of hydrogen atoms and Pt or Bi2Te3 nanoparticles, respectively, which result in introduction of large SOI gaps and subsequent emergence of the 2D TI states. Moreover, I will present that 1T� phase of MoS2, one of TMDC family, which is created by laser beam irradiation, can be within the 2D TI states. These observation must open doors to 2D topological phases of graphene and atom-thin TMDCs and those application to low-power and voltage-controlled spintronics devices.

Biography

J Haruyama is a Professor of Aoyama Gakuin University, Tokyo, and a Visiting Professor of The University of Tokyo, Institute for Solid State Physics. He graduated from Waseda University, Tokyo, Japan, in 1985. Then, he joined Quantum Device Laboratory, NEC Corporation, Japan and worked until 1994. He received his PhD in Physics from Waseda University in 1996. During 1995–1997, he worked with The University of Toronto, Canada, and also Ontario Laser and Lightwave Research Center, Canada as a Visiting Scientist. Since 1997, he has been working at Aoyama Gakuin University. He was also a Visiting Professor at NTT Basic Research Laboratories, Japan, and a Researcher for Zero-emission Energy Center grant, Kyoto University, Japan.

Email:J-haru@ee.aoyama.ac.jp