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MA: Fachverband Magnetismus

MA 42: Magnetic Materials III

MA 42.12: Vortrag

Donnerstag, 3. April 2014, 18:00–18:15, HSZ 04

First-principles simulation of the instability leading to giant magnetocaloric effects — •Peter Entel, Markus Gruner, and Anna Grünebohm — Faculty of Physics and CENIDE, University of Duisburg-Essen, 47048 Duisburg

Ferroic cooling using magnetic solids may lead to a technological breakthrough in future cooling devices. In particular magnetic Heusler alloys such as Ni-Co-Mn-(Ga, In, Sn), and La-Fe-Si, Ga-Mn-C-N and Fe-P based alloys have proven to be suitable for magnetic refrigeration besides the ternary compound Gd-Ge-Si showing giant magnetocaloric effect (MCE). Here, we will address the important aspect of the sudden drop of the magnetization from the ferromagnetic to an antiferromagnetic/paramagnetic state near the magnetostructural transition which is responsible for the giant inverse MCE in some of these systems. We employ density functional theory (DFT) together with finite-temperature Monte Carlo (MC) simulations in the investigations showing that the size of the jump of magnetization in external magnetic fields defines the MCE. Adding elements like Co to the ternary compounds, which is accurately handled in the DFT and MC simulations, allows to explore optimization of the MCE.