Role of Spin Hall Effect in the Topological Side Surface Conduction

Jekwan Lee, Sangwan Sim, Soohyun Park, Chihun In, Seungwan Cho, Seungmin Lee, Soonyoung Cha, Sooun Lee, Hoil Kim, Jehyun Kim, Wooyoung Shim, Jun Sung Kim, Dohun Kim, Hyunyong Choi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The nature of spin transport in the bulk and side surface of three-dimensional topological insulator thin film geometry is a relatively unexplored subject, compared to the extensively studied top and bottom surface states. Here we employ time- and space-resolved helicity-dependent photocurrent measurements to investigate the effect of optically excited bulk carriers on the spin-polarized topological side surface conduction. Time-resolved femtosecond double-pulse excitation reveals that the spin current toward the side surface arises from the bulk-originated spin Hall effect (SHE), whose microscopic origin is governed by an Elliott-Yafet-type spin relaxation mechanism via an extrinsic side jump process. Bias- and temperature-dependent measurements further confirm that the spin scattering in Bi2Se3 has multiple sources including impurity and electron-phonon scattering. The SHE-assisted side surface spin conduction shows an exceptionally high charge-to-spin conversion efficiency of 35% at 77 K, which may offer new spintronic applications of topological insulators such as spin-orbit torque or spin-flip controlled light-emitting devices.

Original languageEnglish
Pages (from-to)3347-3352
Number of pages6
JournalACS Photonics
Volume5
Issue number8
DOIs
Publication statusPublished - 2018 Aug 15

Bibliographical note

Funding Information:
J.L., S.S., S.P., S.C., S.L, C.I., S.C., and H.C. were supported by the National Research Foundation of Korea (NRF) through the government of Korea (MSIP) (grant nos. NRF-2016R1A4A1012929 and NRF-2015R1A2A1A10052520) and the Global Frontier Program (grant no. 2014M3A6B3063709). H.K. and J.S.K. were supported by SRC Center for Topological Matter (grant no. 2011-0030785) and Max-Plank POSTECH/ KOREA Research Initiative (grant no. 2016K1A4A4A01922028). J.K. and D.L. were supported by the Basic Science Research Program through the NRF funded by MSIP (grant no. NRF-2015R1C1A1A02037430).

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biotechnology
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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