Perpendicular magnetic anisotropy and magneto-optical Kerr spectra of MBE-grown PtCo alloy films

Pt/sub 50/Co/sub 50/ alloy films have been grown by MBE method onto heated MgO(100) and (111) substrates. It is found that films grown on a (111) substrate at 300/spl deg/C have the CuPt type structure, whereas films grown onto (111) substrate at 500/spl deg/C and onto (100) substrate at 300/spl deg/C and 400/spl deg/C form in the PtCo ordered phase with AuCu structure. The film of the CuPt type exhibits a very large perpendicular magnetic anisotropy of 1.0/spl times/10/sup 6/ J/m/sup 3/, due to the layered structure along the film normal direction. The spectrum of Kerr rotation /spl theta//sub k/ of the film with CuPt structure is considerably different from that of AuCu structure, not exhibiting a maximum around 4.0 eV but showing a peak at 1.4 eV.