Resonant magneto-tunneling between normal and ferromagnetic electrodes in relation to the three-terminal spin transport

TL;DR

This paper investigates resonant magneto-tunneling between normal and ferromagnetic electrodes, revealing a new interference-based mechanism for spin-dependent current sensitivity that operates even without electron-electron repulsion.

Contribution

It introduces a novel interference-based mechanism for spin transport in resonant tunneling, expanding understanding beyond the previously proposed spin blockade model.

Findings

Sensitivity of current to magnetic fields exists without electron repulsion.

Interference of virtual tunneling amplitudes causes magnetoresistance.

Spin imbalance influences coupling of Zeeman levels and current.

Abstract

The recently suggested mechanism [Y. Song and H. Dery, Phys. Rev. Lett. 113, 047205 (2014)] of the three-terminal spin transport is based on the resonant tunneling of electrons between ferromagnetic and normal electrodes via an impurity. The sensitivity of current to a weak external magnetic field stems from a spin blockade, which, in turn, is enabled by strong on-site repulsion. We demonstrate that this sensitivity exists even in the absence of repulsion when a single-particle description applies. Within this description, we calculate exactly the resonant-tunneling current between the electrodes. The mechanism of magnetoresistance, completely different from the spin blocking, has its origin in the interference of virtual tunneling amplitudes. Spin imbalance in ferromagnetic electrode is responsible for this interference and the resulting coupling of the Zeeman levels. This coupling also affects the current in the correlated regime.