Conductance Discontinuity on the Surface of a Topological Insulator with Magnetic Electrodes

TL;DR

This paper theoretically demonstrates asymmetric conductance on a topological insulator surface caused by magnetic electrodes, highlighting potential applications in low-voltage rectification due to conductance discontinuity.

Contribution

It introduces a transmission matrix model to analyze conductance discontinuity on TI surfaces with magnetic electrodes, considering both ballistic and scattered electron paths.

Findings

Conductance asymmetry can exceed a factor of 10.

Discontinuity depends on spin-momentum locking and electrode coupling.

Potential for practical ratchet and rectification devices.

Abstract

Asymmetric electrical conductance is theoretically demonstrated on the surface of a topological insulator (TI) in the limit of infinitesimally small forward and reverse biases between two spin selective electrodes. The discontinuous behavior relies on the spin-momentum interlocked nature of TI surface electrons together with the resulting imbalance in the coupling coefficients between the electrodes and TI surface states. The analysis is based on a transmission matrix model that, in combination with a phenomenological treatment for the diffusive limit, accounts for both ballistic and scattered paths simultaneously. With the estimated conductance asymmetry over a factor of 10, implementation in the ratchet-like applications and low-voltage rectification circuits appears practicable.