Thermal antiferromagnetism-ferromagnetism transition in (B2-FeRh)-(L1<sub>0</sub>-FePt) composite films
Abstract
FeRh-FePt bilayer films with (001) epitaxy were deposited by magnetron sputtering onto heated MgO(001) substrates, for the purpose of revealing the annealing process to order the both layers without interlayer mixing and investigating their properties of antiferromagnetism-ferromagnetism transition. The results indicate that the FeRh deposited on FePt layer can be ordered by long-time annealing at 450℃, and subsequently a (B2-FeRh)-(L1<sub>0</sub>-FePt) composite bilayer was obtained. The behaviors of antiferromagnetism-ferromagnetism transition were tailored by adjusting the composition of FeRh near equiatomic phase and controlling the ordering level of FePt. The temperature of thermal hysteresis became minus as a Fe-rich FeRh layer deposited on thoroughly ordered FePt layer. The antiferromagnetism-ferromagnetism transition temperature increased from 100℃ to 200℃ typically when the FePt layer was lack of ordering. This shift of magnetic phase transition temperature away from room temperature is helpful for developing thermal assisting magnetic vertical recording media. A concentration threshold of Pt migrating from FePt into FeRh is supposed to discuss the tailoring of antiferromagnetism-ferromagnetism transition.
