Ising films with surface defects

M.-C. Chung, M. Kaulke, I. Peschel
Fachbereich Physik, Freie Universität Berlin, D-14195 Berlin, Germany

M. Pleimling
Institut für Theoretische Physik, Universität Erlangen, D- 91058 Erlangen, Germany

W. Selke
Institut für Theoretische Physik, Technische Hochschule Aachen, D-52056 Aachen, Germany


The influence of surface defects on the critical properties of magnetic films is studied for Ising models with nearest-neighbour ferromagnetic couplings. The defects include one or two adjacent lines of additional atoms and a step on the surface. For the calculations, both density-matrix renormalization group and Monte Carlo techniques are used. By changing the local couplings at the defects and the film thickness, non-universal features as well as interesting crossover phenomena in the magnetic exponents are observed.