Effects of TiN intermediate layer on microstructure and magnetic anisotropy of FePt thin films

Abstract

FePt films were deposited at room temperature on TiN intermediate layer followed by annealing. The effects of TiN layer thickness on the microstructure and magnetic properties of FePt films were investigated. It was found that TiN layer has significant effects on the magnetic anisotropy of the FePt films. The L10 phase transformation of the FePt films with TiN layer was more completely than that without a TiN layer. After annealing at 600 °C, TiN(111) intermediate layer in thickness of 30 nm induced the out-of-plane anisotropy and reached the highest out-of-plane coercivity (4.5 kOe). However, the coercivity was tended to decrease as the thickness of TiN(111) layer increasing to 50 nm. The anisotropy gradually switched from out-of-plane to in-plane when the annealing temperature was increased to 700 °C. The in-plane anisotropy of L10-FePt films may come from the relaxation of internal stress of the TiN layer after annealing at 700 °C, which was not able to provide sufficient in-plane tensile stress to induce the perpendicular growth of L10-FePt grains. Nevertheless, the in-plane coercivity enhanced to 12 kOe when the thickness TiN(111) intermediate layer was 30 nm.