Direct current control of three magnon scattering processes in spin-valve nanocontacts

TL;DR

This study explores how direct current influences spin wave generation and nonlinear magnon scattering in spin-valve nanocontacts, revealing the roles of spin-transfer torque and Oersted fields in these processes.

Contribution

It demonstrates the control of three magnon scattering processes in spin-valve nanocontacts using direct current, highlighting the effects of spin-transfer torque and Oersted fields.

Findings

Direct current affects fundamental spin wave modes via spin-transfer torque.

Oersted fields from current modulate three-magnon scattering efficiency.

Nonlinear modes include integer and non-integer frequency multiples.

Abstract

We have investigated the generation of spin waves in the free layer of an extended spin-valve structure with a nano-scaled point contact driven by both microwave and direct electric current using Brillouin light scattering microscopy. Simultaneously with the directly excited spin waves, strong nonlinear effects are observed, namely the generation of eigenmodes with integer multiple frequencies (2 \emph{f}, 3 \emph{f}, 4 \emph{f}) and modes with non-integer factors (0.5 \emph{f}, 1.5 \emph{f}) with respect to the excitation frequency \emph{f}. The origin of these nonlinear modes is traced back to three magnon scattering processes. The direct current influence on the generation of the fundamental mode at frequency \emph{f} can be related to the spin-transfer torque, while the efficiency of three-magnon-scattering processes is controlled by the Oersted field as an additional effect of the direct current.