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MA: Fachverband Magnetismus

MA 38: Magnetic Materials II

MA 38.8: Vortrag

Donnerstag, 3. April 2014, 11:30–11:45, HSZ 403

Magnetocaloric and hysteretic properties of Ni-Mn based Heusler alloys — •Tino Gottschall, Konstantin Skokov, Bianca Frincu, and Oliver Gutfleisch — TU 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 ΔTad exceeding -8 K at a field change of 2 T in the Ni-Mn-In-(Co) Heusler system. The thermal hysteresis of more than 8 K reduces the magnetocaloric effect drastically when the magnetic field is applied a second time. Nevertheless, we observe a cyclic adiabatic temperature change in the same field change of -3 K when moving in minor loops of magnetization, where only a certain part of the material transforms. The hysteretic behavior of the transition was in situ studied by optical microscopy.