STRUCTURAL AND MAGNETIC STUDIES OF ULTRATHIN EPITAXIAL CO FILMS DEPOSITED ON A PD(111) SINGLE-CRYSTAL

We have studied the structure and magnetic properties of ultrathin epitaxial Pd/Co films deposited by vapor deposition in ultrahigh vacuum on a Pd(111) single crystal. The film crystal structure was characterized by LEED and RHEED and the magnetic properties were studied by Kerr hysteresis loops, vibrating sample magnetometry (VSM) and ferromagnetic resonance (FMR) at 10 and 34 GHz. Well-defined RHEED and LEED patterns were present at all thicknesses proving that there was always a high degree of crystal order in the films despite the large lattice mismatch of 9%. Lattice spacing measurements using RHEED revealed that the Co relaxes to the bulk in-plane spacing in the first monolayer. FMR, Kerr and VSM measurements showed that Co films thinner than almost-equal-to 20 angstrom had an easy magnetization axis perpendicular to the film plane. We deduced that the surface anisotropy constant was (0.80 +/- 0.05) mJ/m2.