Surface-step-induced magnetic anisotropy of p(1x1) Fe on W(100)

Magneto-optic Kerr effect measurements of ultrathin p(1 x 1) Fe films on gr aded-step-density W(100) are used to study step-induced magnetic anisotropy . Spot-profile-analysis low-energy-electron diffraction is used to characte rize the stepped W(100) surface prior to film growth and the epitaxial Fe l ayer after vapor deposition. The experimental results are qualitatively com patible with prior experiments and with theoretical predictions based on th e Neel model and on a one-dimensional micromagnetic model proposed by Hyman , Zangwell, and Stiles (HZS). The observed evolution of hysteresis loop sha pe as a function of step density and anisotropy strength (which was varied by chemisorption of oxygen) is observed to be consistent with a hysteresis loop phase diagram based on the HZS model. However, the measured variation of switching field versus vicinal angle alpha for 2 monolayer thick Fe film s differs significantly from the quadratic dependence predicted by the Neel model and from the dependence predicted by HZS. The surface-step-induced a nisotropy vanishes at high vicinality (alpha similar to 10 degrees) and nov el two-state switching is observed at specific vicinal angles. (C) 2001 Ame rican Institute of Physics.