蒸着法で作製したNi-Fe/Mn-(Ni-Fe)積層膜の構造と交換磁気異方性

抄録

The correlation between the microstructure of the antiferro-magnetic (AF) layer and the unidirectional anisotropy constant (J_k) measured at room temperature was investigated for Ni-Fe 500 Å/Mn_1-x(Ni-Fe)_x 500 Å (x = 0.2-0.5) bilayers. The bilayers were fabricated on the glass substrate with and without a 60-Å-thick Ti buffer layer by the vacuum evaporation method. In the bilayers fabricated directly on the glass substrate, the grain size of the AF layer was about 120 Å and J_k was about 0.02 erg/cm² in the as-deposited state, when x = 0.2-0.3. On the other hand, when the Ti bufffer layer was used, the grain size of the AF layer was enlarged to 200 Å, and J_k was enhanced to 0.06 erg/cm². After annealing at 280°C, the J_k value of the bilayer using the Ti buffer layer reached 0.18 erg/cm², which is 1.5 times larger than without the Ti buffer layer. We concluded that enlargement of the AF grain is one of key factors for enhancing the exchange anisotropy of a ferromagnetic/AF bilayer.