Correlation between Magnetic Phase Transition Temperatures and Lattice Distortions in L10 FePtRh Thin Films

The relationship between magnetic phase transition temperatures (Curie temperature: Tc, ferromagnetic-antiferromagnetic transition temperature: T0) and lattice distortions in L10 FePt1−xRhx thin films (6 nm thick) were studied. Thin film depositions on varied substrates modifies lattice constants due to misfits between substrates and films, as well as residual stresses caused by rapid thermal annealing. Both epitaxially grown FePtRh thin films on MgO(001) substrate and nonepitaxially grown FePtRh thin films on SiO2 substrate exhibited the (001)-oriented L10 structure. The MgO/FePtRh films and the SiO2/FePtRh films had the almost constant a-values of 0.383 nm (1.0% of compressive strain to the FePtRh bulks) and 0.390 nm (0.8% of tensile strain to the FePtRh bulks) in average respectively, whereas the c-values decreased with the Rh composition (x). The c-axis distortion in both the MgO/FePtRh films and the SiO2/FePtRh films were the tensile strain in 0.25