PERPENDICULAR MAGNETIC-BEHAVIOR OF ULTRA-THIN CO SANDWICHES

In situ polar Kerr effect measurements have been used to study the pro perties of MBE-grown X/Co/Y trilayers, where X and Y are combinations of the non-magnetic metals Au, Cu or Pd. Polar hysteresis curves were measured in situ for systematically-varied Co and overlayer Y layer th icknesses 2 Angstrom less than or equal to t(Co) less than or equal to 20 Angstrom and 0 Angstrom less than or equal to t(Y) less than or eq ual to 100 Angstrom. We recently reported that for base layers of Pd o r Au that induce a large perpendicular anisotropy, the magnitude of th e X/Co/Y perpendicular coercivity is strongly peaked at similar or equ al to 1 atomic layer overlayer coverage. However, in Pd overlayers the peak in coercivity is much less pronounced than for the other materia ls. Here we report further measurements on Pd overlayers confirming th e existence of a small peak in coercivity. In addition, measurements h ave been performed on a 'reversed' layered Cu/Co/Au sandwich where the Cu base layer induces only a weak perpendicular anisotropy. We find s imilar peaked behavior similar to that in our earlier measurements on Au/Co/Cu.