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MA: Fachverband Magnetismus

MA 30: Electron Theory

MA 30.12: Vortrag

Donnerstag, 28. Februar 2008, 17:30–17:45, H 1028

Temperature dependent magnetic exchange interactions in the paramagnetic state of hcp Gd. — •Khmelevskyi Sergii, Khmelevska Tetyana, Ruban Andrei, and Mohn Peter — Center for Computational Materials Science, Vienna University of Technology, Gumpendorferstrasse 1, Vienna, Austria, A-1060

We use the first-principles magnetic force theorem embodied in the Korringa-Kohn-Rostoker method to calculate pair magnetic exchange interactions in pure hcp Gd metal in the ferromagnetic as well as in the paramagnetic state with disordered local 4f-moments. It is found that the exchange interactions between the localized 4f-moments, in particular also distant ones, depend on the state of magnetic disorder. Such a dependence is a consequence of the electronic structure changes of the conduction band that mediates the interaction between the local moments. The magnetic ordering temperature has been calculated using a Monte-Carlo simulation technique and the results are compared with mean-field based studies. It is also shown that most important interactions between of nearest neighbors Gd 4f moments is essentially non RKKY in character.