Electrical detection of spin pumping: dc voltage generated by ferromagnetic resonance at ferromagnet/nonmagnet contact

TL;DR

This paper demonstrates electrical detection of spin pumping in metallic nanostructures via dc voltage generated at ferromagnetic resonance, revealing the influence of contact material and device geometry on the effect.

Contribution

It introduces an improved device layout that minimizes rectification effects, enabling clearer detection of spin pumping signals in ferromagnet/nonmagnet contacts.

Findings

Voltage magnitude depends on the spin-relaxation properties of the normal metal.

Using platinum contacts reduces the observed voltage compared to aluminum.

Optimized device geometry minimizes rectification effects.

Abstract

We describe electrical detection of spin pumping in metallic nanostructures. In the spin pumping effect, a precessing ferromagnet attached to a normal-metal acts as a pump of spin-polarized current, giving rise to a spin accumulation. The resulting spin accumulation induces a backflow of spin current into the ferromagnet and generates a dc voltage due to the spin dependent conductivities of the ferromagnet. The magnitude of such voltage is proportional to the spin-relaxation properties of the normal-metal. By using platinum as a contact material we observe, in agreement with theory, that the voltage is significantly reduced as compared to the case when aluminum was used. Furtheremore, the effects of rectification between the circulating rf currents and the magnetization precession of the ferromagnet are examined. Most significantly, we show that using an improved layout device geometry these effects can be minimized.