Nd_2Fe_(14)B/α-Fe界面における交換結合の評価

摘要

Magnetic bilayer films with an interface of α-Fe(100) and Nd_2Fe_(14)B(001) planes were fabricated in order to evaluate the exchange-coupling constant, which was recently reported to depend on the Miller indices of the interface planes. FMR experiments on this film were performed by using a Q-band microwave apparatus. We observed a significant shift of α-Fe resonance field from H_r = 417 kA/m to H_r = 350 kA/m in a bilayer film compared to a reference film without an Nd_2Fe_(14)B layer. This lower shift suggests the existence of an internal field due to the positive exchange coupling between α-Fe and Nd_2Fe_(14)B phases. The magnitude of the exchange-coupling constant was estimated to be in the range between 6.5×10~(-3) J/m~2 for the bilayer film.%UHVマグネトロンスパッタ法を用いて，α-Fe(100)/Nd_2Fe_(14)(001)界面を有する2層膜を作製し，層間の交換結合について強磁性共鳴を用いて評価した.レファレンスとして作製したα-Fe(100)単層膜の共鳴磁場(H_r = 417 kA/m)に対して，α-Fe(100)/Nd_2Fe_(14)B(001)膜におけるα-Fe層の共鳴磁場(H_r = 350 kA/m)が低磁場側にシフトしたことから，両層間に正の交換結合が働いていることが示唆された.この共鳴磁場のシフト量から交換結合定数J_(ex)を見積もったところ，J_(ex)= 6.5×10~(-3)J/m~2となった.