MAGNETIC-PROPERTIES AND MICROSTRUCTURAL ANALYSIS OF SPUTTER-DEPOSITED AND ANNEALED CO-PT ALLOYS

We have produced Co1-xPtx (x=0.53 and 0.75) alloy films by dc magnetron sputtering at various substrate temperatures (RT-300°C) and sputtering pressures (2-10 mTorr). The magnetic properties of the films were examined by using vibrating sample magnetometry and Kerr hysteresis loop tracer. A (111) texture is observed in the as-deposited film, and its degree is dependent on the substrate temperature and Ar pressure. The degree of the (111) texture does not affect the magnetic anisotropy. While the magnetic properties of the Co0.25Pt0.75 alloy films are not sensitive to heat treatment, the coercivity and the loop squareness of the Co0.47Pt0.53 alloy films are drastically increased by annealing. Structural analysis using transmission electron microscopy and x-ray diffractometry reveals that CoPt(L10) and CoPt3(L1 2) ordered phases, respectively, are formed, each with a strong (111) texture. By comparing the magnetic properties between the CoPt(L10) and CoPt3(L12) ordered phases in relation to the atomic arrangements in a unit cell, it is concluded that the perpendicular magnetic anisotropy in the sputter-deposited Co-Pt alloy system depends mainly on the atomic arrangements of the Co and Pt. © 1995 American Institute of Physics.