Low Magnetic Damping of Epitaxial NiFe (100) Thin Films Grown on Different Substrate

Abstract

The magnetic properties and Gilbert damping constant α of NiFe films grown on different substrates at different sputtering temperatures were investigated. NiFe films with low Gilbert damping constant α of 0.0046 (TiN) and 0.0055 (MgO) at 500°C were obtained. It is found that the crystal structure and lattice mismatch strongly affected the Gilbert damping constant α. With increasing the sputtering temperature, the NiFe gradually changed from amorphous to crystalline, thus the chemical ordering increased, which would cause the decrease of the density of states at Fermi level (D(EF)) and the Gilbert damping constant α. Moreover, the damping constant exhibited a slight decrease with increasing the mismatch strain, which would be further proven by the spin resolved density of states for the NiFe films. This study may offer a fabrication method of the NiFe films with small damping constant α in the applications of the STT-MRAM device’s area.