Effect of Sputtering Gases on Crystallographic Structure and Magnetic Property of Mn-Ir/Co-Fe Bilayers

Abstract

  The crystallographic structure of Mn-Ir layers and the magnetic property of Mn-Ir/Co-Fe bilayers were investigated for Ar pressure, P_Ar, and Kr pressure, P_Kr, for the deposition of the Mn-Ir layer. When Ar was used as the sputtering gas, the blocking temperature, T_B, was steeply decreased with decreasing P_Ar, and became T_B=220°C at P_Ar=0.04 Pa. However, in the case of Kr gas, T_B was 320°C at P_Kr=0.04 Pa. The surface roughness, R_a, of bilayers at P_Ar=0.04 Pa was lowered, comparing to that at P_Kr=0.04 Pa. The X-ray diffraction profiles showed that the superlattice diffractions from the ordered Mn₃Ir phase were detected around the pressures P_Ar=0.2 Pa-2.0 Pa and P_Kr=0.04 Pa-2.0 Pa. In P_Ar≤0.1 Pa, the damage cased by the recoiled Ar ions was suggested as an origin of the decreasing T_B and the disappearance of Mn₃Ir phase.