Concepedia

Spin Pumping with Coherent Elastic Waves

Mathias Weiler, Hans Huebl, Frederik Goerg, Franz D. Czeschka, Sebastian T. B. Goennenwein

Physical Review Letters · 2012 · 262 citations · 26 references

Open access

TL;DR

Surface acoustic wave pulses at 1.55 GHz and 300 ns duration generate coherent elastic waves in a Co/Pt bilayer, and the resulting spin current is quantified via the inverse spin Hall voltage in Pt as a function of time, magnetic field magnitude, and orientation. The experiments demonstrate that resonant phonon–magnon coupling produces room‑temperature spin currents only under resonant elastic excitation, establishing acoustic spin pumping as a resonant analogue of the spin Seebeck effect.

Abstract

We show that the resonant coupling of phonons and magnons can be exploited to generate spin currents at room temperature. Surface acoustic wave (SAW) pulses with a frequency of 1.55 GHz and duration of 300 ns provide coherent elastic waves in a ferromagnetic thin film/normal metal (Co/Pt) bilayer. We use the inverse spin Hall voltage in the Pt as a measure for the spin current and record its evolution as a function of time and external magnetic field magnitude and orientation. Our experiments show that a spin current is generated in the exclusive presence of a resonant elastic excitation. This establishes acoustic spin pumping as a resonant analogue to the spin Seebeck effect.