Formation of stable nanoscaled magnetic FePt films for high-density magnetic recording and information storage
It is developed new approach for diffusion formation of stable nanoscaled magnetic-hard FePt films with chemically ordered L10(FePt)FCT phase at using additional layers of alloying elements (Ag, Au, Cu) with low surface energy. The energy of interface between layers was applied as additional superior-driving force for acceleration of thermally activated processes of chemical ordering FePt film and decreasing of temperature (~ 100oC) of phase transformation of chemically disordered magnetic-soft А1(FePt)FCC to chemically ordered magnetic-hard L10(FePt)FCT phase with superstructure. It is proved reasonability using of alloying elements (Ag, Au, Cu) with limited solubility in FePt alloy for effective management on parameters and crystalline superlattice orientation as well as limitation of grain growth and arrangement of easy magnetization axis perpendicularly to substrate surface. It is carried out complex experimental investigations of multi-layer nanoscaled film systems that allowed to form L10(FePt)FCT phase with high coercivity (Нс ~ 20 - 30 кОе), saturation magnetization (~ 1500 emu/cm3), with rectangular shape of magnetization curve and Mr/Ms ratio of 1 in surface layers. It is developed proposals on choice of technological parameters of formation and stabilization process of FePt films. Application of these films will allow to increase density magnetic recording and information storage by heat-assisted magnetic recording up ~ 250 Gbit/сm2 instead of reached now 60 Gbit/сm2.