Detection of the Spin-Chemical Potential in Topological Insulators Using Spin-Polarized Four-Probe STM

Saban M. Hus, X. G. Zhang, Giang D. Nguyen, Wonhee Ko, Arthur P. Baddorf, Yong P. Chen, An Ping Li

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38 Scopus citations

Abstract

We demonstrate a new method for the detection of the spin-chemical potential in topological insulators using spin-polarized four-probe scanning tunneling microscopy on in situ cleaved Bi2Te2Se surfaces. Two-dimensional (2D) surface and 3D bulk conductions are separated quantitatively via variable probe-spacing measurements, enabling the isolation of the nonvanishing spin-dependent electrochemical potential from the Ohmic contribution. This component is identified as the spin-chemical potential arising from the 2D charge current through the spin momentum locked topological surface states (TSS). This method provides a direct measurement of spin current generation efficiency and opens a new avenue to access the intrinsic spin transport associated with pristine TSS.

Original languageEnglish
Article number137202
JournalPhysical Review Letters
Volume119
Issue number13
DOIs
StatePublished - Sep 27 2017

Funding

This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The crystal growth and characterization at Purdue was supported by DARPA MESO program (Grant No. N66001-11-1-4107).

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