Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.108: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
Magnetocaloric effect of magnetic molecules with single-ion-anisotropy — •Julian Ehrens, Christian Beckmann, and Jürgen Schnack — Universität Bielefeld, PF 100131, D-33501 Bielefeld
The magnetocaloric effect can fundamentally be described as the change of temperature when materials are exposed to changing magnetic fields in e.g. adiabatic processes. Along this line, magnetocaloric properties of isotropic spin systems, that are modeled by a Heisenberg Hamiltonian augmented with a Zeeman term, have been investigated extensively [1]. Magnetic molecules with single-ion-anisotropy such as Mn12, whose ground state multiplet can be approximated as the multiplet of a single giant spin with dominating easy axis, enable the use of rotating magnetic fields or rotating samples to exploit the magnetocaloric effect. Here we report investigations being made for giant spin models with various spin quantum numbers employing several thermodynamic cycles including the successive rotation around different axes in order to find the maximum entropy difference for best cooling performance.
[1] J.W. Sharples, D. Collison, E.J.L. McInnes, J. Schnack, E. Palacios, M. Evangelisti, Nature Communications 5 (2014) 5321