Effect of TiN-ZrO2 intermediate layer on the microstructure and magnetic properties of FePt and FePt-SiO2-C thin films

The microstructures and magnetic properties of FePt based thin films grown on TiN-ZrO2 and TiN-ZrO2/TiN intermediate layers were systematically investigated. The TiN-ZrO2 intermediate layer was granular consisting of grains of solid solution of Ti(Zr)ON segregated by amorphous ZrO2. It was found with doping ZrO2 into TiN intermediate layer, grain size of FePt-SiO2-C films significantly decreased. Simultaneously, the isolation was obviously improved and grain size distribution became more uniform. However, the magnetic properties of the FePt-SiO2-C films grown on TiN-ZrO2 intermediate layers were slowly deteriorated, which was due to the disturbance of the epitaxial growth of FePt by amorphous ZrO2 in TiN-ZrO2 intermediate layer. In order to improve the TiN-ZrO2 (0 0 2) texture and the crystallinity of TiN-ZrO2, TiN-ZrO2/TiN combined intermediate layer was introduced. And the magnetic properties were improved, simultaneously, achieving the benefit of grain size reduction. For the FePt 4 nm-SiO2 40 vol%-C 20 vol% film grown on TiN/TiN-ZrO2 30 vol% combined intermediate layer, well isolated FePt (0 0 1) granular films with coercivity higher than 17.6 kOe and an average size as small as 6.5 nm were achieved.