Suppression of spin-torque in current perpendicular to the plane spin-valves by addition of Dy cap layers

TL;DR

This paper shows that adding Dy capping layers to spin-valves significantly raises the current density threshold for spin-torque instabilities, enabling higher current operation with manageable noise levels.

Contribution

It introduces Dy capping layers as a method to suppress spin-torque effects in CPP spin-valves, increasing critical current density threefold.

Findings

Critical current density increased by about three times.

Dy capped samples exhibit low 1/f noise.

High current densities up to 5e7 A/cm2 achieved.

Abstract

We demonstrate that the addition of Dy capping layers in current perpendicular to the plane giant magneto-resistive spin-valves can increase the critical current density beyond which spin-torque induced instabilities are observed by about a factor of three. Current densities as high as 5e7 A/cm2 are measured provided that the electron current flows from the free to the reference layer. While Dy capped samples exhibit nonmagnetic 1/f noise, it is sufficiently small to be unimportant for read head operation at practical data rates.