Periodic Table of Impurity Damping in Doped Permalloy Thin Films

This paper presents a survey of the effects of transition metal doping on the damping properties of thin films of Permalloy (Ni
₈₀
Fe
₂₀
). For many applications requiring high speed or high data rates, the magnetization of Permalloy is underdamped, and this results in magnetization precession with a lifetime of a few nanoseconds. In these materials, faster switching could be accomplished by increased damping. The coupling to the thermal bath that allows magnetic energy to dissipate is also responsible for driving thermal fluctuations of the magnetization. These fluctuations are observable in small sensors as magnetization noise. For these applications, the noise limit of the sensor could be improved with reduced damping.