Determination of critical thickness of spin reorientation in metastable magnetic ultrathin films

We investigate the spin reorientation of structurally unstable magnetic ultrathin films ~base films! using magnetic capping layers. The capping layers, whose effective anisotropy constant is opposite that of the base films, are grown on the base films with no transformed structure and induce a spin reorientation after exceeding a critical thickness. The critical thickness of the capping layers can be used to deduce the critical thickness as well as the anisotropy constants of the base films. We use Co to cap the well-known Fe/Cu~100! system as an example to demonstrate the proposed approach. © 1999 American Institute of Physics. @S0003-6951~99!02145-2#