Mn3Ir/Co-Fe積層膜のL12規則相形成に及ぼすスパッタガス種の影響

The crystallographic structure of Mn-Ir layers and the exchange anisotropy of Mn-Ir/Co-Fe bilayers were investigated for various process pressures and sputtering gases used in the deposition of the Mn-Ir layers. When Ar was used as the sputtering gas, the unidirectional anisotropy constant JK was found to decrease with decreasing Ar pressure PAr. However, in the case of Kr gas, JK was shown to be constant at about 1.0 erg/cm2, regardless of the Kr pressure PKr. In particular, JK exceeded 1.0 erg/cm2 for PKr ≤ 0.1 Pa. The x-ray diffraction profiles showed that superlattice diffractions from the ordered Mn3Ir phase were detected around the pressures PAr = 0.2 Pa − 2.0 Pa and PKr = 0.04 Pa − 2.0 Pa. In the case where PAr ≤ 0.1 Pa, the damage caused by the recoiled Ar ions is suggested to be the origin of the decreasing JK and the disappearance of Mn3Ir phase.