Regensburg 2016 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MA: Fachverband Magnetismus
MA 23: Magnetic Materials and Caloric Effects
MA 23.4: Talk
Tuesday, March 8, 2016, 14:45–15:00, H32
Inelastic neutron scattering on magnetocaloric compounds — •Nikolaos Biniskos1, Karin Schmalzl1, Stephane Raymond2, and Thomas Brueckel3 — 1Juelich Center for Neutron Science JCNS, Forschungszentrum Juelich GmbH, Outstation at ILL, Grenoble, France — 2CEA-Grenoble, INAC SPSMS MDN, Grenoble, France — 3Juelich Centre for Neutron Science JCNS and Peter Gruenberg Institut PGI, JARA-FIT, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany
One way for saving energy in daily life is using the magnetocaloric effect (MCE), i.e. the change of magnetic entropy and adiabatic temperature following a change in an applied magnetic field. The ferromagnetic compound MnFe4Si3 (S.G.: P-6) is a promising candidate for applications. It has a magnetic phase transition in the range of 300 K and shows a moderate MCE of 2.9 J/kg K at a reasonable magnetic field change from 0 T to 2 T. In order to understand the fundamental driving force of the MCE in this material a study of magnetism, lattice dynamics and their interaction is necessary. Energy scans and q-scans first with non-polarized neutron scattering were carried out at energies mainly below 13meV looking for lattice (acoustic phonons) and magnetic excitations. Later these excitations were identified with polarized neutrons. Preliminary results at 1.5K indicate stronger magnetic interactions in [001] than [100] direction of the hexagonal system. Measurements with polarized neutrons above TC reveal sizable magnetic fluctuations in a significant large temperature range (300<T<500K). Magnetic fluctuations in the paramagnetic phase are found to be isotropic.