Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 10: Caloric Effects in Ferromagnetic Materials
MA 10.4: Vortrag
Montag, 20. März 2017, 16:00–16:15, HSZ 04
Spin dynamics of magnetocaloric compound Mn5Si3 — •Nikolaos Biniskos1,2, Karin Schmalzl1, Stephane Raymond2, Sylvain Petit3, and Thomas Brueckel4 — 1JCNS, Forschungszentrum Juelich GmbH, Outstation at ILL, Grenoble, France — 2CEA-Grenoble, INAC MEM, 38054 Grenoble, France — 3CEA-CNRS UMR 12, IRAMIS LLB, 91190 Gif-sur-Yvette, France — 4JCNS and PGI, JARA-FIT, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany
The magnetocaloric effect (MCE) refers to a change of entropy of a magnetic material exposed to a magnetic field change. A large MCE at room temperature and low magnetic field for a material with abundant and environmentally friendly elements opens the way for magnetic cooling devices. Inelastic neutron scattering (INS) studies might point out ingredients that may favor large MCE. From the Mn5-xFexSi3 series the parent compound Mn5Si3 exhibits positive and negative magnetic entropy change in relation with two distinct antiferromagnetic phase transitions at TN1=66K (AF1: non-collinear, non-coplanar structure) and TN2=99K (AF2: collinear structure), respectively. Experiments performed on a single crystal with unpolarized INS in the paramagnetic (PM) state and in the AF2 and AF1 phases revealed that AF1 is characterized by sharp spin-waves, but AF2 is characterized by a diffuse signal that resembles the one of the PM state, indicating strong spin fluctuations.