Phase investigation in Pt supported off-stoichiometric iron-platinum thin films

The structural and magnetic phase transformation of Pt/Fe3Pt/Pt films on Si <1 0 0> substrates prepared by DC magnetron sputtering is investigated as a function of annealing temperature. Pt diffusion driven low temperature phase transformation from A1 to L10 phase is achieved at 300 °C, attaining a very high coercivity of 9 kOe. At 300 °C, 85% L10 phase transformation is observed using the X-ray diffraction profile fitting. The estimated phase content is also further verified by fitting the demagnetization curve. The underlayer promotes the ordering at lower temperature while overlayer induces growth along (0 0 1) preferred orientation. Rutherford back scattering study reveals interlayer diffusion and confirms the desired stoichiometry for L10 phase. The presence of Pt under-overlayer provides the Pt source and further facilitates the Pt diffusion, which makes it effective in promoting the phase ordering at a lower temperature.