title: Room Temperature Electrical Detection of Spin Polarized Currents in Topological Insulators.
abstract: 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.
authors.affiliation: Department of Microtechnology and Nanoscience, Chalmers University of Technology , SE 41296 Göteborg, Sweden.
authors.forename: André
authors.initials: A
authors.lastname: Dankert
authors.affiliation: Department of Microtechnology and Nanoscience, Chalmers University of Technology , SE 41296 Göteborg, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Geurs
authors.affiliation: Department of Microtechnology and Nanoscience, Chalmers University of Technology , SE 41296 Göteborg, Sweden.
authors.forename: M Venkata
authors.initials: MV
authors.lastname: Kamalakar
authors.affiliation: Department of Microtechnology and Nanoscience, Chalmers University of Technology , SE 41296 Göteborg, Sweden.
authors.forename: Sophie
authors.initials: S
authors.lastname: Charpentier
authors.affiliation: Department of Microtechnology and Nanoscience, Chalmers University of Technology , SE 41296 Göteborg, Sweden.
authors.forename: Saroj P
authors.initials: SP
authors.lastname: Dash
mesh_terms: D004560:Electricity; D013696:Temperature
keywords: Bi2Se3; Topological insulators; ferromagnetic tunnel contacts; room temperature; spin polarized surface states; spin-momentum locking