Opposite current-induced spin polarizations in bulk-metallic Bi2Se3 and bulk-insulating Bi2Te2Se topological insulator thin flakes

Jifa Tian; Cuneyt Sahin; Ireneusz Miotkowski; Michael E. Flatte; Yong P. Chen

doi:10.1103/PhysRevB.103.035412

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Opposite current-induced spin polarizations in bulk-metallic Bi2Se3 and bulk-insulating Bi2Te2Se topological insulator thin flakes

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Opposite current-induced spin polarizations in bulk-metallic Bi2Se3 and bulk-insulating Bi2Te2Se topological insulator thin flakes

Jifa Tian, Cuneyt Sahin, Ireneusz Miotkowski, Michael E. Flatte and Yong P. Chen

Physical review. B, Vol.103(3), 035412

01/14/2021

DOI: 10.1103/PhysRevB.103.035412

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https://arxiv.org/pdf/2008.09899View

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Abstract

One of the most fundamental and exotic properties of three-dimensional (3D) topological insulators (TIs) is spin-momentum locking (SML) of their topological surface states (TSSs), promising for potential applications in future spintronics. However, other possible conduction channels, such as a trivial two-dimensional electron gas (2DEG) with strong Rashba-type spin-orbit interaction (SOI) and bulk-conducting states that may possess a spin Hall effect (SHE), can coexist in 3D TIs, making determining the origin of the current-induced spin polarization (CISP) difficult. In this work, we directly compared the CISP between bulk-insulating Bi2Te2Se (BTS221) and bulk-metallic Bi2Se3 thin flakes using spin potentiometry. In the bulk-insulating BTS221, the observed CISP has a sign consistent with the expected helicity of the SML of the TSS, but an opposite sign to its calculated bulk spin Hall conductivity. However, compared to BTS221, an opposite CISP is observed in the bulk-metallic Bi2Se3, consistent with both the expectations of its Rashba-Edelstein effect of the band-bending induced 2DEG and bulk intrinsic spin Hall Effect (SHE). If one assumes a representative occupation of the Rashba band of 3 x 10(13) cm(-2) in Bi2Se3 with a relevant relaxation time of 100 fs, the contribution to the CISP could be more dominated by the bulk intrinsic SHE. Our results provide an electrical way to distinguish the TSS from other possible conducting channels in spin transport measurements on 3D TIs, and open ways for the potential applications in charge-spin conversion devices.

Materials Science

Physical Sciences

Physics

Technology

Materials Science, Multidisciplinary

Physics, Applied

Physics, Condensed Matter

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Details

Title: Subtitle: Opposite current-induced spin polarizations in bulk-metallic Bi2Se3 and bulk-insulating Bi2Te2Se topological insulator thin flakes
Creators: Jifa Tian - Purdue University West Lafayette
Cuneyt Sahin - University of Iowa
Ireneusz Miotkowski - Purdue University West Lafayette
Michael E. Flatte - University of Iowa
Yong P. Chen - Purdue University West Lafayette
Resource Type: Journal article
Publication Details: Physical review. B, Vol.103(3), 035412
DOI: 10.1103/PhysRevB.103.035412
ISSN: 2469-9950
eISSN: 2469-9969
Publisher: Amer Physical Soc
Number of pages: 8
Grant note: DE-SC0020074; DE-SC0021281 / DOE, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering; United States Department of Energy (DOE) Lockheed Martin Corporation DMR-1420451 / Center for Emergent Materials, an NSF MRSEC; National Science Foundation (NSF) N66001-11-1-4107 / DARPA MESO program; United States Department of Defense EFMA-1641101 / NSF; National Science Foundation (NSF) DOE Office of Science through the Quantum Science Center (QSC), a National Quantum Information Science Research Center; United States Department of Energy (DOE)
Language: English
Date published: 01/14/2021
Academic Unit: Electrical and Computer Engineering; Physics and Astronomy
Record Identifier: 9984428828502771

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