Spin-charge locking and tunneling into a helical metal
Institut für Physik, Universität Augsburg - 86135 Augsburg, Germany, EU
2 CNISM and Dipartimento di Fisica “E. Amaldi”, Università Roma Tre - 00146 Roma, Italy, EU
3 Institut de Physique et Chimie des Matériaux de Strasbourg (UMR 7504), CNRS and Université de Strasbourg 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France, EU
Accepted: 28 February 2011
We derive a kinetic equation for the electrons moving on the surface of a three-dimensional topological insulator. Due to the helical nature of the excitations backward scattering is suppressed in the collision integral, and the spin dynamics is entirely constrained by that of the charge. We further analyze the tunneling between the helical metal and a conventional metal or ferromagnet. We find that the tunnel resistance strongly depends on the angle between the magnetization in the ferromagnet and the current in the helical metal. A nonmagnetic layer on top of the helical metal amplifies the current-induced spin polarization.
PACS: 72.25 Ba – / 72.25 Mk –
© EPLA, 2011