2-DIMENSIONAL ISING TRANSITION OF EPITAXIAL FE FILMS GROWN ON AG(100)

Fe(100) films and wedges between 2 and 4 monolayers thick were grown o nto a Ag(100) single-crystal substrate. High- and low-energy electron- diffraction observations confirm the epitaxy. The magnetic phase trans ition near the Curie temperature T(C) was investigated in situ by mean s of the surface magneto-optic Kerr effect. The temperature dependence of the magnetization follows a universal power law of M(T) is-proport ional-to (1 - T/T(C))beta(c) with an effective value of beta(c) almost -equal-to 1/8(0.124+/-0.002), which indicates that the phase transitio n is two-dimensional Ising class. This and the observed perpendicular easy axes are attributed to the surface magnetic anisotropy.