Abstract
The study of magnetism and crystallography of nanostructures is one of the most challenging topics, at present. Novel structures were grown, which do not exist in the bulk; the magnetism of these nano-sized particles and films may differ from the bulk by orders of magnitude. Synergistic applications of theory and experiment in materials science are all important for a fundamental understanding. The most important parameters are the magnetic anisotropy energy (MAE) and the interlayer exchange coupling (IEC) in multilayers. We will discuss examples where ab-initio calculations adapted to existing experiments disentangle the importance of surface and volume effects in the MAE, as well as a layer-resolved IEC and its T-dependence. The Weinberger group has unambiguously shown that the ‘volume part’ of the MAE is most important to understand the spin reorientation transition (SRT) in Ni/Cu. They also calculated the IEC layer-by-layer in the T = 0 limit for a trilayer. Very recently, in theory, spin wave excitations were added to interpret the experimental findings.
Acknowledgements
We are very grateful to the theorists who picked up our experimental findings and helped to form a more fundamental understanding of MAE and IEC in ultrathin ferromagnets. These are the groups of P. Weinberger, O. Eriksson and B. Johansson, D.L. Mills and R. Wu, K.-H. Bennemann and W. Nolting. The experiments would not have been possible without my former coworkers: J. Lindner, K. Lenz, S. S. Kalarickal, E. Kosubek, and X. Xu. In particular E. Kosubek and K. Lenz are acknowledged for assistance in preparing this manuscript. This work was supported in part by BMBF (05KS4 KEB/5) and DFG Sfb 658.