Spin injection from topological insulator tunnel-coupled to metallic leads

Abstract

We study theoretically helical edge states of 2D and 3D topological insulators (TI) tunnel-coupled to metal leads and show that their transport properties are strongly affected by contacts as the latter play a role of a heat bath and induce damping and relaxation of electrons in the helical states of TI. A simple structure that produces a pure spin current in the external circuit is proposed. The current and spin current delivered to the external circuit depend on relation between characteristic lengths: damping length due to tunneling, contact length and, in case of 3D TI, mean free path and spin relaxation length caused by momentum scattering. If the damping length due to tunneling is the smallest one, then the electric and spin currents are proportional to the conductance quantum in 2D TI, and to the conductance quantum multiplied by the ratio of the contact width to the Fermi wavelength in 3D TI.

References in corpus (5)

• Spintronics and Pseudospintronics in Graphene and Topological Insulators
• The Quantum Spin Hall Effect: Theory and Experiment
• Full electrical control of Charge and Spin conductance through Interferometry of Edge States in Topological Insulators
• Spin-Charge Locking and Tunneling into a Helical Metal
• Spin current in an electron waveguide tunnel-coupled to topological insulator

Cited by in corpus (1)

• On the accuracy of conductance quantization in spin-Hall insulators