Room Temperature Electrical Detection of Spin Polarized Currents in Topological Insulators
Journal article, 2015

Topological insulators (TIs) are a new class of quantum materials that exhibit a current-induced spin polarization due to spin-momentum locking of massless Dirac Fermions in their surface states. This helical spin polarization in three-dimensional (3D) TIs has been observed using photoemission spectroscopy up to room temperatures. Recently, spin polarized surface currents in 3D TIs were detected electrically by potentiometric measurements using ferromagnetic detector contacts. However, these electric measurements are so far limited to cryogenic temperatures. Here we report the room temperature electrical detection of the spin polarization on the surface of Bi2Se3 by employing spin sensitive ferromagnetic tunnel contacts. The current-induced spin polarization on the Bi2Se3 surface is probed by measuring the magnetoresistance while switching the magnetization direction of the ferromagnetic detector. A spin resistance of up to 70 mΩ is measured at room temperature, which increases linearly with current bias, reverses sign with current direction, and decreases with higher TI thickness. The magnitude of the spin signal, its sign, and control experiments, using different measurement geometries and interface conditions, rule out other known physical effects. These findings provide further information about the electrical detection of current-induced spin polarizations in 3D TIs at ambient temperatures and could lead to innovative spin-based technologies.

ferromagnetic tunnel contacts

Bi2Se3

spin-momentum locking spin polarized surface states

Topological insulators

room temperature

Author

André Dankert

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Johannes Geurs

Chalmers, Microtechnology and Nanoscience (MC2)

Venkata Kamalakar Mutta

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Sophie Charpentier

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Saroj Prasad Dash

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Nano Letters

1530-6984 (ISSN) 1530-6992 (eISSN)

Vol. 15 12 7976-7981

Areas of Advance

Information and Communication Technology

Nanoscience and Nanotechnology (2010-2017)

Energy

Materials Science

Subject Categories

Physical Sciences

Nano Technology

Roots

Basic sciences

DOI

10.1021/acs.nanolett.5b03080

More information

Created

10/8/2017