Field-Free Synthetic-Ferromagnet Spin Torque Oscillator

TL;DR

This paper investigates a field-free spin torque oscillator using a synthetic ferromagnet in a spin valve, demonstrating current-induced magnetization precession without external magnetic fields through analytical and numerical methods.

Contribution

It introduces a novel field-free spin torque oscillator based on a synthetic ferromagnet with analytical stability analysis and numerical validation.

Findings

Precessional states can be excited without external magnetic fields.

Analytical stability analysis matches numerical simulations.

Current density and exchange coupling control magnetization dynamics.

Abstract

We study the magnetization dynamics of spin valve structures with a free composite synthetic ferromagnet (SyF) that consists of two ferromagnetic layers coupled through a normal metal spacer. A ferromagnetically coupled SyF can be excited into dynamical precessional states by an applied current without external magnetic fields. We analytically determine the stability of these states in the space spanned by the current density and SyF interlayer exchange coupling. Numerical simulations confirm our analytical results.