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Regensburg 2016 – scientific programme

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MA: Fachverband Magnetismus

MA 23: Magnetic Materials and Caloric Effects

MA 23.5: Talk

Tuesday, March 8, 2016, 15:00–15:15, H32

Designing cubic Heusler for magnetocaloric-based applications — •Luana Caron1, Sanjay Singh1, Sunil W. D’Souza1, Tina Fichtner1, Giacomo Porcari2, Simone Fabbrici3, Chandra Shekhar1, Stanislav Chadov1, Massimo Solzi2, and Claudia Felser11Max Planck Institute for Chemical Physics of Solids, Germany — 2Parma University, Italy — 3IMEM-CNR, Italy

Since the observation of a giant magnetocaloric effect (MCE) in Gd5Ge2Si2, the search for materials for MCE-based applications has been focused on compounds showing 1st order phase transitions. However, the practical application of giant MCE materials is hindered by the nature of the transition itself. In order to drive a 1st order phase transition, energy is spent to overcome the energy barrier between different states. This energy loss leads to irreversibilities in both temperature and entropy changes in addition to discontinuous structural changes which cause physical instability. In this work we explore theoretically and experimentally how to obtain high magnetic moments in cubic Ni2(Mn,X)2 X= Ga, In, Sn Heusler alloys. Our aim is to design Heusler compounds presenting a combination of high ground state moment and a fully reversible 2nd order phase transition for magnetocaloric cooling applications. Using ab initio calculations we have determined the exchange interactions and magnetic moments of these alloys in the cubic structure as to maximize the net saturation magnetization. As a proof of concept we present the magnetic and MCE properties of the Ni2Mn1.4In0.6 compound which presents a calculated and measured saturation moment comparable to that of Gd.

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