First-principles study on interface magnetic structure in Nd2Fe14B/(Fe,Co) exchange springmagnets

The magnetic properties of Nd2Fe14B (NFB)/transition metal (TM = Fe, Co) multilayersystems are studied on the basis of first-principles density functional calculations. Weoptimize the model structure under a variety of crystallographic alignments of the NFB layer,and analyze the mechanism of interface magnetic coupling. Improvements in remanentmagnetization compared to that of single NFB are observed in NFB(001)/Fe, NFB(110)/Fe,and NFB(100)/Co. On the other hand, in NFB(100)/Fe, remanence degradation due to theanti-parallel magnetization alignment between NFB and Fe layers is observed. In this system,which has the shortest optimized interlayer distance among all considered systems, anitinerant electron magnetism is required around the interface to lower the total energy, andaccordingly, anti-ferromagnetic coupling is preferred. The significant difference in propertybetween NFB(100)/Fe and NFB(100)/Co is attributed to the difference between theirinterface structures, optimized interlayer distances, and magnetic stiffness of TM layers.

This work was supported by CREST-JST