Sustained Amplification of Coherent Spin Waves by Parametric Pumping with Surface Acoustic Waves

TL;DR

This paper demonstrates sustained amplification of coherent spin waves in a yttrium-iron-garnet film using surface acoustic waves as a pump, achieving up to 6 dB gain and enabling active magnonic components.

Contribution

It introduces a novel method of using traveling surface acoustic waves for parametric amplification of spin waves, showing stable, frequency- and wavevector-selective gain.

Findings

Achieved up to 6 dB gain in spin waves

Generated an idler wave consistent with three-wave mixing

Demonstrated stable amplification below the parametric instability threshold

Abstract

Parametric amplification offers a route to overcoming intrinsic damping in spin-wave systems, a key challenge in the development of magnonic signal processing and computing technologies. Here we demonstrate the sustained amplification of coherent forward volume magnetostatic spin waves in a yttrium-iron-garnet thin film using a traveling surface acoustic wave as a nonstationary pump. A gain of up to 6 dB is achieved under continuous pumping below the threshold for parametric instability. The interaction generates an idler wave at a distinct frequency, consistent with three-wave mixing governed by energy and momentum conservation. This approach enables stable, frequency- and wavevector-selective spin-wave gain using practical pump power levels, establishing acoustic wave pumping as a viable mechanism for realizing active components in integrated magnonic circuits.