Direct Observation of a Localized Magnetic Soliton in a Spin-Transfer Nanocontact

Phys Rev Lett. 2015 Sep 18;115(12):127205. doi: 10.1103/PhysRevLett.115.127205. Epub 2015 Sep 17.

Abstract

We report the direct observation of a localized magnetic soliton in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments are conducted on a lithographically defined 150 nm diameter nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element-resolved x-ray magnetic circular dichroism images show an abrupt onset of a magnetic soliton excitation localized beneath the nanocontact at a threshold current. However, the amplitude of the excitation ≃25° at the contact center is far less than that predicted (⪅180°), showing that the spin dynamics is not described by existing models.