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MA: Fachverband Magnetismus
MA 10: Magnetic Materials
MA 10.8: Vortrag
Montag, 25. Februar 2008, 17:00–17:15, H 1028
Magnetocaloric effect in nickel rich Ni-Mn-Ga Heusler alloys — Kalyan Mandal1, 2, Julia Lyubina2, Debabrata Pal1, Nils Scheerbaum2, and •Oliver Gutfleisch2 — 1Magnetism Laboratory, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098, India — 2Leibniz Institute für Festkörper- und Werkstoffforschung Dresden (IFW Dresden), Institut für Metallische Werkstoffe, Postfach 270116, 01171 Dresden, Germany
Heusler alloys with nickel-rich compositions Ni(2+x)Mn(1-x)Ga (x=0.16, 0.18, 0.20, 0.22, 0.24, 0.26) have been prepared by arc-melting and subsequent annealing. A large magnetic entropy change, |DS| ~96 J/Kg.K has been observed around 291 K for the composition Ni(2.22)Mn(0.78)Ga where the martensite-austenite structural transition almost coincides with ferromagnetic-paramagnetic magnetic transition. The effect of hydrostatic pressure up to 8kbar on martensitic transition, magnetic transition and magnetocaloric effect has been studied. The martensitic transition temperature as well as the Curie temperature Tc was found to increase whereas |DS| decreases slightly due to the application of hydrostatic pressure. The large hysteresis observed in M vs H curve at ambient pressure was reduced significantly at 8kbar.