The fabrication of high quality FeCo alloy ultra-thin films via the nitrogen-surfactant effect toward fabrication of L1_0-FeCo thin films

摘要

L1_0-type ordered alloy is attracting attention as a rare earth free high-performance magnet and magneticstorage device because of its high magnetic anisotropy, saturation magnetization, and high Curietemperature. Among them, an L1_0-type ordered FeCo alloy (L1_0-FeCo) without noble metals wastheoretically predicted to have extremely high perpendicular magnetic anisotropy . Previously, L1_0-FeCothin films were prepared by the precisely-controlled growth of alternating Fe and Co monolayers usingpulsed laser deposition . However, the perpendicular magnetization has not yet been achieved becauseL1_0 atomic structure at the Fe/Co interface is not sufficiently ordered. For realizing high quality L1_0-FeCofilms, we here focus on the fabrication method utilizing the nitrogen surfactant effect in the thin-filmgrowth of transition-metals. High lateral lattice stability of the monatomic-layer nitrides such as Fe_2N onCu (001) , and nitrogen surfactant effect during the deposition of Fe and Co monolayers can suppress thediffusion at the Fe/Co interface. These will lead to atomically flat and homogeneous surface and interfacein the L10-FeCo thin films.