Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 41: Magnetic Coupling Phenomena

MA 41.3: Vortrag

Donnerstag, 10. März 2016, 10:00–10:15, H33

Antiferromagnetism in ordered and disordered full Heusler compounds — •Eszter Simon, György J. Vida, András Deák, Sergii Khmelevskyi, and László Szunyogh — University of Technology and Economics, Budapest, Hungary

The growing technological demand for spintronics applications raised increased interest for searching novel antiferromagnets (AFM). Promising candidates are the full Heusler compounds like Ni2MnAl in the B2 phase or Ru2MnZ (Z= Si, Ge) having Néel temperature above the room temperature. In this contribution we present a study of these alloys based on first-principles calculations of interatomic Mn-Mn exchange interactions. Chemical disorder is taken into account in terms of the coherent potential approximation. By setting up a suitable Heisenberg spin model we performed Monte Carlo simulations of the magnetic properties at finite temperature.

In case of Ru2MnSi, our numerical results suggest that suppressing the intermixing between the Mn and Si atoms, the Néel temperature can potentially be increased by more than 30% [1]. For Ni2MnAl, a systematic study from the ordered L21 to the disordered B2 phase shows a progressive change from the FM state to a fully compensated AFM state, due to strong AFM site-antisite Mn-Mn interactions [2].

As an input for the study of potential exchange bias effects, we also present calculated spin-model parameters for the interface between these Heusler alloys and bcc Fe.

[1] S. Khmelevskyi et al., Phys. Rev. B 91, 094432 (2015)

[2] E. Simon et al., Phys. Rev. B 92, 054438 (2015)