Roughness dependent magnetic hysteresis of a few monolayer thick Fe films on Au(001)

We have studied quantitatively the surface and interface roughness of Fe films in a few monolayer regime on an Au(001) surface using the high-resolution low-energy electron diffraction technique. The hysteresis loops of those films were also measured in situ by the surface magneto-optical kerr effect technique. A correlation between the shape of hysteresis loops and the roughness of films was observed. The hysteresis loops are consistently squarelike for films with a two-dimensional (2D) smooth structure. For films with isolated three-dimensional (3D) islands structure, the hysteresis loops are typically stripelike. For films with a combination of 2D/3D structure, the loop shape is squarelike for longitudinal loops and stripelike for polar loops.