Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 45: Joint Session "Magnetic Shape Memory Alloys II" (jointly with DS, MM)
MA 45.3: Vortrag
Donnerstag, 29. März 2012, 15:30–15:45, H 0112
Dynamic simulation of the giant magnetocaloric effect in Ni-Mn-based Heusler alloys — •Tino Gottschall1, Jian Liu1, Konstantin Skokov1, James David Moore1, and Oliver Gutfleisch1,2 — 1IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany — 22Technische Universität Darmstadt, Institut für Materialwissenschaft, Petersenstr. 23, 64287 Darmstadt, Germany
The origin for the inverse magnetocaloric effect in Ni-Mn-based Heusler alloys is a first-order magnetostructural transition between a low temperature paramagnetic/antiferromagnetic martensite and a high temperature ferromagnetic austenite phase. Performing direct measurements, we report a large adiabatic temperature change Δ Tad exceeding -6 K at a field change of 2 T in a novel Ni-Mn-In-(Co) alloy. Such a giant magnetocaloric effect makes them potential candidates for energy efficient magnetic refrigeration. Far from an ideal first-order transition material, a wide transition temperature range was observed in this sample probably due to the existence of a local inhomogeneity over the sample. The transition distribution has the shape of a Gaussian function. Based on these considerations we were able to simulate the temperature change under adiabatic conditions, which agrees very well with the experimental data. Three parameters to manipulate the dynamic cooling process, namely field dependency, transition width and potential temperature change, are discussed for an in-depth understanding of the underlying physics behind the observed giant magnetocaloric effect.