Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 23: Magnetic Materials and Caloric Effects

MA 23.1: Vortrag

Dienstag, 8. März 2016, 14:00–14:15, H32

The influence of magnetocrystalline anisotropy on the magnetocaloric effect studied in Co₂B — •Maximilian Fries¹, Konstantin P. Skokov¹, Dmitriy Y. Karpenkov¹, Vicotrino Franco², Semih Ener¹, and Oliver Gutfleisch¹ — ¹Technische Universität Darmstadt, Materialwissenschaft, Darmstadt, Germany — ²Sevilla University, Dpto. Fisica de la Materia Condensata, Sevilla, Spain

Since the discovery of the magnetocaloric effect many promising material families like LaFeSi and Fe₂P-based alloys have been extensively studied. In addition, it has been found that especially the Fe₂P-type materials show large magnetocrystalline anisotropy which strongly influences the magnetocaloric properties. In order to quantify the influence of magnetocrystalline anisotropy on the magnetocaloric effect, we studied a single crystal of tetragonal Co₂B by means of magnetometry and adiabatic temperature change measurements. It is found that especially in fields smaller than 2 T the effect of anisotropy plays a significant role. In a field change of 1 T the MCE differs 50% from one to the other axis and 30% in 2 T in a temperature range bewteen 400 and 440K respectively. This behaviour will be explained by the rotational MCE. It is shown that especially in the aimed scenario of using magnetocaloric materials in rather small magnetic fields achievable by permanent magnets the effect of anisotropy needs to considered. We therefore propose utilizing textured non-cubic magnetocaloric materials with easy axis of magnetization parallel to the applied field in a device in order to increase the overall efficiency.