LOCAL STRUCTURAL AND POLAR KERR EFFECT MEASUREMENTS ON AN ULTRATHIN EPITAXIAL CO WEDGE GROWN ON PD(111)

A Pd/Co double layer has been grown epitaxially in ultrahigh vacuum on a Pd(111) single crystal, with the Co in the shape of a wedge of thickness varying from 0 to 10 monolayers (ML). The polar magneto-optical Kerr effect has been used to make a nearly continuous set of measurements of the magnetic properties as a function of Co thickness t(Co). The coercive fields H(c) and nucleation fields H(n) show large, well-defined maxima at t(Co) approximately 2.3 ML. Between 4 and 9 ML, we find that H(c) falls with increasing thickness according to a t(Co)-5/2 dependence. The Kerr ellipticity and Kerr rotation depend linearly on Co thickness above approximately 2 ML Co, but show appreciable offsets when extrapolated to t(Co)=0. These offsets are clear evidence of the polarization of Pd near the interfaces. Extensive in situ growth studies of the structure of the films are also reported.