‘ๆ42‰๑ ŒดŒคE•บŒง‘ๅ‡“ฏƒRƒƒLƒEƒ€

“๚Žž: •ฝฌ20”N5ŒŽ20“๚(‰ฮ) 16F00`
Date and time: 20th May (Tue.) 16:00`
๊Š: SPring-8, –GŒ๕Šู
Place: SPring-8, "HOUKOUKAN" seminar room
Title: Theory of diluted ferromagnetic semiconductors
Speaker: Prof. Timothy Ziman (Institut Laue Langevin and CNRS, Grenoble and IMR, Tohoku University)
Abstract:

Despite intense activity, both experimental and theoretical, in the subject of dilute ferromagnetic semiconductors, there is still not a clear understanding of the ferromagnetism. This is partly to do with a lack of systematic studies to fully characterize different samples. Studies of doped III-V materials have improved the situation, and it should now be possible to compare different theoretical models with more controlled experiments. One approach has been to use effective magnetic Hamiltonians derived from ab initio methods which in conjunction with Monte Carlo or semi-analytic methods can give good agreement with experimental values of Curie temperatures for uncompensated and annealed samples. Another approach is to find simple models which capture the essential ingredients for ferromagnetism. I will discuss the theoretical issues with particular reference to questions that may be clarified by scattering experiments: microscopic couplings, doping dependence of samples, inhomogeneities and the like. I will also discuss ideas related to the possibility of gdefect-induced ferromagnetismh in oxides as indicated by recent experiments.