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MA: Fachverband Magnetismus
MA 15: Magnetic Heuslers, Half-metals and Oxides (jointly with TT)
MA 15.4: Vortrag
Montag, 20. März 2017, 15:45–16:00, HSZ 403
Defect-induced magnetic structure of CuMnSb — •Frantisek Maca1, Josef Kudrnovsky1, Vaclav Drchal1, and Ilja Turek2 — 1Institute of Physics ASCR, Praha, Czech Republic — 2Charles University, Faculty of Mathematics and Physics, Praha, Czech Republic
We have investigated the magnetic phases of CuMnSb Heusler alloy with defects which exist in real experimental conditions. Total energy calculations confirm that the AFM[100]-phase is the ground state for the ideal CuMnSb in contrast to the experimentally observed AFM[111]-phase. Calculated formation energies indicate as possible candidates for defects the Cu-Mn swaps for the stoichiometric alloy and Mn-antisites on Cu-lattice and Mn-interstitials for Mn enriched alloys.
The total energies of various magnetic phases of CuMnSb with defects were determined using two different structural models, namely, the full-potential supercell approach and the alloy model employing the coherent potential approximation (CPA). We have found that the AFM[111]-ground state is stabilized for a low critical impurity concentrations approximately 3% . We have also investigated the influence of defects on the exchange interactions among Mn-moments and the stability of magnetic order by using the Heisenberg model Hamiltonian. The stability of the AFM[111] phase is in all cases enhanced by electron correlations in narrow Mn-bands treated here in the static limit (LDA+U).