Spin configuration of Gd clusters and thin films (abstract)

Studies of the magnetism and structure of Gd clusters and surfaces will be presented.1 The spin configuration of a Gd13 cluster and the Gd(0001) surface has been examined using electronic structure calculations as well as a Heisenberg model. Structural calculations show that the ground-state geometry of the cluster has a hcp arrangement with a slightly reduced nearest-neighbor distance compared to bulk and an average moment of 7.8 μB/atom. The Heisenberg model is calculated using a Ruderman-Kittel-Kasuya-Yosida-like interaction. The effects of competing ferromagnetic and antiferromagnetic coupling for the nearest- and next-nearest neighbor interaction, respectively, is investigated. It is shown that for a range of interaction strengths the spins in the cluster assume a canted configuration. This effect leads to lower net magnetization of the cluster, and accounts for the anomalous low moments of Gdn clusters that have been experimentally observed. A similar model of the Gd(0001) surface agrees well with earlier spin resolved low-energy electron diffraction experiments from Gd/W(110), and spin resolved secondary electron spectroscopy studies of the surface magnetism of Gd grown on Y(0001) will be presented.