Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Poster 2

MA 35.31: Poster

Donnerstag, 8. September 2022, 16:00–18:00, P4

Heat capacities and Curie curve in the Stoner and Heisenberg models — •Nabil Makadir, Stephanie Roden, Sanjay Ashok, Sebastian T. Weber, Felix Dusabirane, H. Christian Schneider, and Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, TU Kaiserslautern, Germany

The excitation of a metallic ferromagnet with an ultrashort laser pulse leads to a demagnetization on the femtosecond timescale. The response of the material is governed by macroscopic properties, like the heat capacities and the equilibrium magnetization (Curie curve). They can be calculated for instance with either the Stoner model or the Heisenberg model. The former attributes the change of magnetization to the shifting of the spin-resolved density of states. The latter describes the reduction of the magnetization through collective angular oscillation of the individual magnetic moments.

In this contribution, we derive the temperature-dependent heat capacities and the Curie curves for Nickel. We compare the results of the Stoner and the Heisenberg model and analyze the advantages and drawbacks of both approaches. Finally, we investigate the transition between Stoner and Heisenberg excitations.