Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 14: INNOMAG e.V. Dissertationspreis 2018 / Ph.D. Thesis Prize

MA 14.1: Hauptvortrag

Montag, 12. März 2018, 15:00–15:25, H 0112

On the magnetocaloric properties of Heusler compounds — •Tino Gottschall — TU Darmstadt, Institute of Material Science, Germany

Large magnetocaloric effects can be obtained in the Heusler alloys Ni-Mn-In and Ni-Mn-In-Co during the magnetostructural phase transformation between the low-temperature paramagnetic martensite and the high-temperature ferromagnetic austenite phase. The martensitic transition is furthermore sensitive to a magnetic field but also to hydrostatic pressure. It can therefore be induced by those external stimuli [1]. However, the existence of thermal hysteresis in those materials limits the reversible adiabatic temperature and isothermal entropy change. The magnetocaloric effect under cycling can be enhanced in so-called minor loops of hysteresis [2]. On the contrary, in very high magnetic-field rates as well as in micrometer-sized single particles, the thermal hysteresis increases significantly [3]. In order to understand the contrasting behavior of small fragments compared to bulk, a finite element model is introduced, from which the importance of mechanical stress during the transition becomes apparent [4].

[1] T. Gottschall et al., Phys. Rev. B 93, 184431 (2016).

[2] T. Gottschall et al., Appl. Phys. Lett. 106, 021901 (2015).

[3] T. Gottschall et al., Phys. Rev. Applied 5, 024013 (2016).

[4] T. Gottschall et al., Adv. Funct. Mater. 27, 1606735 (2017).