Direct Observation of Large Amplitude Spin Excitations Localized in a Spin-Transfer Nanocontact

TL;DR

This study directly visualizes large amplitude, localized spin excitations in a nanocontact, revealing the formation of magnetic solitons driven by spin-transfer torque in a perpendicular magnetic anisotropy multilayer.

Contribution

It provides the first direct imaging evidence of localized spin excitations and magnetic solitons in a nanocontact using advanced x-ray microscopy techniques.

Findings

Localized spin excitations occur abruptly at a threshold current.

Spin precession cone angles reach approximately 25 degrees.

Evidence suggests the observed excitations are magnetic solitons.

Abstract

We report the direct observation of large amplitude spin-excitations localized in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments were conducted using a nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element resolved x-ray magnetic circular dichroism images show an abrupt onset of spin excitations at a threshold current that are localized beneath the nanocontact, with average spin precession cone angles of 25{\deg} at the contact center. The results strongly suggest that we have observed a localized magnetic soliton.