Mechanically Induced Thermal Breakdown in Magnetic Shuttle Structures

TL;DR

This paper presents a theoretical model of thermally induced electron shuttling instability in a magnetic nanomechanical device, revealing how temperature and magnetic fields influence shuttle behavior and potential thermal energy harvesting.

Contribution

It introduces a new theory describing thermally driven electron shuttling in magnetic nanostructures, highlighting the effects of temperature and magnetic fields on instability regimes.

Findings

Shuttling occurs within specific magnetic field ranges depending on temperature.

Upper critical magnetic field saturates at high temperatures.

Shuttle instability domain expands as temperature decreases.

Abstract

A theory of a thermally induced single-electron "shuttling" instability in a magnetic nanomechanical device subject to an external magnetic field is presented in the Coulomb blockade regime of electron transport. The model magnetic shuttle device considered comprises a movable metallic grain suspended between two magnetic leads, which are kept at different temperatures and assumed to be fully spin polarized with antiparallel magnetizations. For a given temperature difference shuttling is found to occur for a region of external magnetic fields between a lower and an upper critical field strength, which separate the shuttling regime from normal small-amplitude "vibronic" regimes. We find that (i) the upper critical magnetic field saturates to a constant value in the high temperature limit and that the shuttle instability domain expands with a decrease of the temperature, (ii) the lower critical magnetic field depends not only on the temperature independent phenomenological friction coefficient used in the model but also on intrinsic friction (which vanishes in the high temperature limit) caused by magnetic exchange forces and electron tunneling between the quantum dot and the leads. The feasibility of using thermally driven magnetic shuttle systems to harvest thermal breakdown phenomena is discussed.