Spin-transfer-assisted parametric pumping of magnons in yttrium iron garnet

TL;DR

This paper investigates how combining parametric pumping and spin-transfer torque influences magnon excitations and their instabilities in yttrium iron garnet thin films, providing insights into magnetic control mechanisms.

Contribution

It offers a theoretical analysis and micromagnetic simulations of the combined effects on magnon instabilities, highlighting the tuning of thresholds by spin-transfer torque.

Findings

Spin-transfer torque adjusts the instability thresholds.

The combined effects enable enhanced control over magnon excitations.

Results align with experimental observations.

Abstract

The combination of parametric pumping and spin-transfer torque is a powerful approach that enables high-level control over magnetic excitations in thin-film ferromagnets. The excitation parameters, such as pumping power and external field strength, affect the instabilities of individual magnon modes. We theoretically explore how the simultaneous effects of parametric pumping and spin transfer torque influence these magnetic instabilities in a thin-film ferromagnet. Within the Landau-Lifshitz-Gilbert framework, we perform micromagnetic simulations of magnon excitations in yttrium iron garnet by pumping, spin transfer torque, and a combination of the two. We find that consistent with experimental results, the magnitude and direction of the spin-transfer torque tune the parametric instability thresholds.