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MA: Fachverband Magnetismus

MA 18: Topical session: Caloric Effects in ferroic materials I - Magnetocalorics

MA 18.3: Talk

Tuesday, March 8, 2016, 11:00–11:15, H53

Understanding the magnetostructural transitions of first-order materials — •Tino Gottschall, Dimitri Benke, Konstantin Skokov, Maximilian Fries, Iliya Radulov, and Oliver Gutfleisch — TU Darmstadt, Material Science, Darmstadt, Germany

The large magnetocaloric effect in the most promising first-order materials like La-Fe-Si [1], Fe2P type materials [2] or Heusler alloys [3] originates in the strong change of the magnetization with temperature being associated with a structural transformation. All these materials have one thing in common. The so-called magnetostructural transition goes hand in hand with a large volume change or at least a large change of the c to a ratio of the crystal structure.

In this work we present magnetic measurements of micrometer sized single particles of the three mentioned materials and compare them with the transformation characteristics of the corresponding bulk properties. It turns out that a very different behavior is observed depending on the size of the magnetocaloric sample. This result is of great importance for the application of magnetic refrigeration, especially for the design of powder bed heat exchangers.

This work was supported by DFG (Grant No. SPP1599)

[1] I.A. Radulov, K.P. Skokov, D.Yu. Karpenkov, T. Gottschall, O. Gutfleisch, J. Mag. Mag. Mater. 396 (2015) 228 [2] F. Guillou, H. Yibole, G. Porcari, L. Zhang, N.H. van Dijk, E. Brück, J. Appl. Phys. 116 (2014) 063903 [3] T. Gottschall, K.P. Skokov, B. Frincu, O. Gutfleisch, Appl. Phys. Lett. 106 (2015) 021901