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

We demonstrate that the addition of Dy capping layers in current perpendicular to the plane giant magnetoresistive spin-valves can increase the critical current density beyond which spin-torque induced instabilities are observed by about a factor of three. While Dy capped samples exhibit nonmagnetic 1/f noise, it is sufficiently small to be unimportant for read head operation at practical data rates.