Switching of perpendicularly magnetized nanomagnets with spin-orbit torques in the absence of external magnetic fields

Patent metadata

Field	Value
Publication number	US-11626229-B2
Application number	US-202117231277-A
Country	US
Kind code	B2
Filing date	Apr 15, 2021
Priority date	May 8, 2015
Publication date	Apr 11, 2023
Grant date	Apr 11, 2023

Abstract

A method of controlling a trajectory of a perpendicular magnetization switching of a ferromagnetic layer using spin-orbit torques in the absence of any external magnetic field includes: injecting a charge current Je through a heavy-metal thin film disposed adjacent to a ferromagnetic layer to produce spin torques which drive a magnetization M out of an equilibrium state towards an in-plane of a nanomagnet; turning the charge current Je off after te seconds, where an effective field experienced by the magnetization of the ferromagnetic layer Heff is significantly dominated by and in-plane anisotropy Hkx, and where M passes a hard axis by precessing around the Heff; and passing the hard axis, where Heff is dominated by a perpendicular-to-the-plane anisotropy Hkz, and where M is pulled towards the new equilibrium state by precessing and damping around Heff, completing a magnetization switching.

First claim

What is claimed is:

1. A method of controlling a trajectory of a perpendicular magnetization switching of a ferromagnetic layer using spin-orbit torques in the absence of any external magnetic field comprising:
injecting a charge current J e through a heavy-metal thin film disposed adjacent to a nanomagnet comprising a shape having a long axis and a short axis of a ferromagnetic layer to produce spin torques which drive a magnetization M out of an equilibrium state towards an in-plane of a nanomagnet, a flow of electrical charge of said charge current J e non-perpendicular to said short axis of said nanomagnet;
turning said charge current J e off after t e seconds, causing a spin torque to reduce to substantially zero where M is close to an x-y plane and away from an e z axis by an angle of ϑ in a critical zone, where an effective field experienced by the magnetization of the ferromagnetic layer H eff is significantly dominated by and in-plane anisotropy H kx , and where M passes a hard axis by precessing around said H eff ; and
passing the hard axis, where H eff is dominated by a perpendicular-to-the-plane anisotropy H kz , and where M is pulled towards the new equilibrium state by precessing and damping around H eff , completing a magnetization switching.

2. The method of claim 1 , wherein a duration of said t e of an applied current pulse comprises a shortest time which causes said magnetization M to move from said equilibrium state to said critical zone.

Assignees

• Univ Rochester

Inventors

• Kazemi Mohammad
• Friedman Eby G
• Ipek Engin

Classifications

• H10N50/85

  Materials of the active region · CPC title

• H10N50/20

  Spin-polarised current-controlled devices (magnetoresistive devices H10N50/10) · CPC title

• H03K19/18

  using galvano-magnetic devices, e.g. Hall-effect devices · CPC title

• H01F10/329

  Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect · CPC title

• H10N52/80

  Constructional details · CPC title