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 language | English |
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Article number | 137202 |
Journal | Physical Review Letters |
Volume | 119 |
Issue number | 13 |
DOIs | |
State | Published - 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).