Single-spin polaron memory effect

TL;DR

This paper investigates a minimal polaron model of a quantum dot with a single spin, revealing how bias voltage influences spin switching, hysteresis, and control mechanisms, with potential applications in spintronics.

Contribution

It introduces a model showing bias-tunable spin switching and hysteresis in a quantum dot system with electron-vibron interactions, proposing a control method via a third contact.

Findings

Spin switching rate is suppressed at zero bias.

Hysteretic behavior enables controlled spin switching.

Bias voltage controls spin lifetime, current, and polarization.

Abstract

The single-spin memory effect is considered within a minimal polaron model describing a single-level quantum dot interacting with a vibron and weakly coupled to ferromagnetic leads. We show that in the case of strong electron-vibron and Coulomb interactions the rate of spontaneous quantum switching between two spin states is suppressed at zero bias voltage, but can be tuned through a wide range of finite switching timescales upon changing the bias. We further find that such junctions exhibit hysteretic behavior enabling controlled switching of a spin state. Spin lifetime, current and spin polarization are calculated as a function of the bias voltage by the master equation method. We also propose to use a third tunneling contact to control and readout the spin state.