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

The magnetic properties and Gilbert damping constant a of NiFe films grown on different substrates at different sputtering temperatures were investigated. NiFe films with low Gilbert damping constant a of 0.0046 (TiN) and 0.0055 (MgO) at 500 degrees C were obtained. It is found that the crystal structure and lattice mismatch strongly affected the Gilbert damping constant alpha. 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(E-F)) and the Gilbert damping constant alpha. 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 a in the applications of the STT-MRAM device's area.

Automated summary

The study found that crystal structure and lattice mismatch strongly influenced the Gilbert damping constant of NiFe films. Increasing the sputtering temperature led NiFe to transition from amorphous to crystalline, resulting in increased chemical ordering and decreased damping constant. Additionally, an increase in mismatch strain was found to slightly decrease the damping constant, which was further supported by spin resolved density of states analysis.