Nonequilibrium spin distribution in single-electron transistor

TL;DR

This paper theoretically investigates how tunneling current induces nonequilibrium spin distributions in a ferromagnetic single-electron transistor, revealing magnetoresistance dips and potential negative values related to spin-dependent Fermi level shifts.

Contribution

It introduces a theoretical model for nonequilibrium spin distributions in ferromagnetic single-electron transistors, highlighting the impact on magnetoresistance behavior.

Findings

Magnetoresistance ratio exhibits dips related to spin-dependent Fermi level separation.

Inside dips, the magnetoresistance ratio can become negative.

Tunneling current causes nonequilibrium spin distributions in the device.

Abstract

Single-electron transistor with ferromagnetic outer electrodes and nonmagnetic island is studied theoretically. Nonequilibrium electron spin distribution in the island is caused by tunneling current. The dependencies of the magnetoresistance ratio $\delta$ on the bias and gate voltages show the dips which are directly related to the induced separation of Fermi levels for electrons with different spins. Inside a dip $\delta$ can become negative.