Out-of-plane auto-oscillation in spin Hall oscillator with additional polarizer

TL;DR

This paper theoretically explores how adding an extra polarizer in spin Hall oscillators enables out-of-plane auto-oscillations, which could enhance microwave-assisted magnetic recording technologies.

Contribution

It introduces a novel approach to induce out-of-plane auto-oscillations in in-plane magnetized ferromagnets via an additional polarizer, expanding the control of magnetization dynamics.

Findings

Out-of-plane auto-oscillations can be excited in in-plane ferromagnets.

Manipulation of spin-transfer torque direction through ferromagnet relaxation.

Potential application in microwave-assisted magnetic recording.

Abstract

The theoretical investigation on magnetization dynamics excited by the spin Hall effect in metallic multilayers having two ferromagnets is discussed. The relaxation of the transverse spin in one ferromagnet enables us to manipulate the direction of the spin-transfer torque excited in another ferromagnet, although the spin-polarization originally generated by the spin Hall effect is geometrically fixed. Solving the Landau-Lifshitz-Gilbert-Slonczewski equation, the possibility to excite an out-of-plane auto-oscillation of an in-plane magnetized ferromagnet is presented. An application to magnetic recording using microwave-assisted magnetization reversal is also discussed.