Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 10: Caloric Effects in Ferromagnetic Materials

MA 10.3: Talk

Monday, March 20, 2017, 15:45–16:00, HSZ 04

Substitutional influences on the magnetocaloric properties of the MnNiGe-system — •Andreas Taubel, Tino Gottschall, Konstantin Skokov, and Oliver Gutfleisch — Alarich-Weiss-Straße 16, 64287 Darmstadt

Magnetocaloric materials exhibit a temperature change when placed within a magnetic field under adiabatic conditions. They are studied intensively in order to make it a competitive and more energy efficient cooling technology besides gas compression [1]. The MM'X material system of Mn-Ni-Ge attracts recently significant interest for magnetocalorics because of a sharp and nicely tunable phase transition. The transition temperature can be tuned by Fe substitution for Ni or Mn, which additionally induces ferromagnetic interactions and establishes large magnetization changes.

In our work, the influence of elemental substitutions on the Ge site is studied in detail. The substitution of Si for Ge reduces the amount of expensive Ge and enhances the ferromagnetic behavior leading to a favored transition behavior in low fields. Moreover the mechanical stability of the samples is enhanced compared to brittle MnNiGe, which is important towards utilization of the material for cooling cycles. The high volume change during phase transition is responsible for the initial instability but enables significant pressure tuning, especially for the Si substituted samples. Further substitutions with Al and Sn can be done to completely renounce expensive Ge.

This work was supported by DFG (Grant No. SPP1599).

[1] O. Gutfleisch et al., Adv. Mater. 23, 821-842 (2011)