Current-driven ferromagnetic resonance, mechanical torques and rotary motion in magnetic nanostructures

TL;DR

This paper explores how electric currents induce mechanical torques and motion in magnetic nanostructures, analyzing voltage signals, detecting vibrations, and proposing a spin-transfer-driven nanomotor for potential applications.

Contribution

It introduces a theoretical framework for detecting current-induced mechanical effects and proposes a novel spin-transfer-driven nanomotor concept.

Findings

DC voltage signals reveal magnetostatic and dynamic properties.

Vibrations cause measurable splitting of voltage resonance.

A new design for a spin-transfer-driven electric nanomotor is proposed.

Abstract

We study theoretically the detection and possible utilization of electric current-induced mechanical torques in ferromagnetic-normal metal heterostructures that are generated by spin-flip scattering or the absorption of transverse spin currents by a ferromagnet. To this end, we analyze the DC voltage signals over a spin valve that is driven by an AC current. In agreement with recent studies, this "rectification", measured as a function of AC frequency and applied magnetic field, contains important information on the magnetostatics and --dynamics. Subsequently, we show that the vibrations excited by spin-transfer to the lattice can be detected as a splitting of the DC voltage resonance. Finally, we propose a concept for a spin-transfer-driven electric nanomotor based on integrating metallic nanowires with carbon nanotubes, in which the current-induced torques generate a rotary motion.