PERPENDICULAR MAGNETIC-ANISOTROPY IN COXPD1-X ALLOY-FILMS GROWN BY MOLECULAR-BEAM EPITAXY

We have grown face-centered cubic (FCC) (111)- and (001)-oriented CoxP d1-x alloy films (x-0.20-0.25) by molecular beam epitaxy on (111)Si an d (001)MgO substrates, respectively, with thicknesses almost-equal-to 200-1000 angstrom. Magnetization (SQUID) measurements show that both ( 111) and (100) films present a perpendicular easy axis, indicating tha t a strong magnetic anisotropy overcomes the demagnetizing field favor ing the in-plane orientation. We have studied this magnetic anisotropy by combining SQUID and torque measurements. Our experimental results cannot be accounted for by only invoking the magnetocrystalline anisot ropy of a disordered solid solution of Co in FCC Pd, and rather indica te an anisotropic distribution of Co in the Pd host.