Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.53: Poster

Freitag, 26. März 2010, 11:00–14:00, Poster B1

Magnetic fluctuations in FeRh. — •Leonid Sandratskii — Max Planck Institute of Microstructure Physics, Halle, Germany

FeRh experiences a first-order phase transition antiferromagnet-ferromagnet at about 350 K and can be treated as a natural magnetic multilayer system where large magnetoresistance can be easily realized. Recent time-resolved pump and probe experiments have shown an ultra-fast transition to the ferromagnetic state within femtosecond time scale. Despite much efforts devoted to the study of FeRh the nature of the phase transition remains the matter of debates. Although it is now clear that the Rh moments play crucial role in the stabilization of the ferromagnetic phase there is no consensus with respect to the selection of the magnetic degrees of freedom to describe the thermodynamical equilibruium. Some researches assume that the Rh moments are uniquely determined by the Fe environment and therefore should not be considered as separate degrees of freedom. Other groups consider the Rh moment as a separate Heisenberg or Ising variable. We use density-functional theory to study the spectrum of magnetic excitations in FeRh. Both transversal and longitudinal atomic fluctuations are considered. The study provides deeper insight into the nature of the Rh moment and the connection between the fluctuations of the Fe and Rh magnetization.