# Detection of current induced spin polarization in epitaxial Bi$_2$Te$_3$ thin film

## TL;DR

This paper reports the electrical detection of spin polarization induced by charge current on the surface of epitaxial Bi$_2$Te$_3$ thin films, confirming the spin-polarized surface states through experimental and theoretical analysis.

## Contribution

It demonstrates the electrical detection of current-induced spin polarization in epitaxial Bi$_2$Te$_3$ thin films using a two-terminal device with ferromagnetic contacts, combining experimental measurements with theoretical estimates.

## Key findings

- Hysteresis in resistance correlates with Fe magnetization
- Order of magnitude and sign match spin-polarized surface states
- Theoretical estimates support experimental observations

## Abstract

We electrically detect charge current induced spin polarization on the surface of molecular beam epitaxy grown Bi$_2$Te$_3$ thin film in a two-terminal device with a ferromagnetic MgO/Fe and a nonmagnetic Ti/Au contact. The two-point resistance, measured in an applied magnetic field, shows a hysteresis tracking the magnetization of the Fe. A theoretical estimate is obtained for the change in resistance on reversing the magnetization direction of Fe from coupled spin-charge transport equations based on quantum kinetic theory. The order of magnitude and the sign of the hysteresis is consistent with spin-polarized surface state of Bi$_2$Te$_3$.