(B2-FeRh)-(L1_0-FePt)复合双层薄膜的热致反铁磁-铁磁转变

Thermal antiferromagnetism-ferromagnetism transition in(B2-FeRh)-(L1_0-FePt) composite films

用磁控溅射法在加热的MgO(001)基片上生长FeRh-FePt双层取向薄膜,试图使两层都有序化并分析其反铁磁-铁磁转变性质.结果表明,覆盖于FePt层之上的FeRh层可以在不发生层间混合的前提下,于450°C依靠长时间热处理出现有序化,从而获得较为理想的(B2-FeRh)-(L10-FePt)双层复合薄膜.改变FeRh层的成分和控制FePt层的有序化程度能够裁剪其反铁磁-铁磁转变行为.在彻底有序化的FePt层上生长富Fe的FeRh层会导致热滞温度为负.而FePt层适当欠有序化则可以将反铁磁-铁磁转变温度由100°C提高到200°C,使其进一步远离室温.这有利于用来制作采用热辅助技术的垂直磁记录介质.从Pt扩散阈值的角度对反铁磁-铁磁转变举动变化的可能原因进行了讨论.

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）-（L10-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.