Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Magnetic Heusler Compounds I

MA 35.6: Vortrag

Mittwoch, 28. März 2012, 16:45–17:00, H 0112

Pressure dependence of Curie temperature and resistivity of complex Heusler alloys — •Vaclav Drchal¹, Shyamal Bose², Josef Kudrnovsky¹, and Ilja Turek³ — ¹Institute of Physiscs AS CR, Praha, Czech Republic — ²Brock University, St. Catharines, Canada — ³Institute of Physics of Materials, AS CR, Brno, Czech Republic

Using first-principles electronic structure methods, we have calculated the Curie temperature and resistivity of random quaternary Heusler alloys (Ni_1−xPd_x)₂MnSn and (Ni_1−xCu_x)₂MnSn [1] and studied their dependence on the external hydrostatic pressure [2]. The Curie temperatures were calculated within the random-phase approximation applied to the Heisenberg Hamiltonian, whose parameters were determined using the density functional theory. The Curie temperature increases with pressure in (Ni_1−xPd_x)₂MnSn alloys for all concentrations x while the crossover from the increase to the decrease of the Curie temperature with pressure takes place for x > 0.7 in (Ni_1−xCu_x)₂MnSn Heusler alloys. The spin-disorder induced part of the resistivity in (Ni_1−xPd_x)₂MnSn Heusler alloys, calculated by using the disordered local moment model, is presented. Finally, we discuss qualitatively the results on the basis of Anderson’s superexchange and Stearn’s model of the indirect exchange between localized and itinerant d-electrons.

[1] S.K. Bose et al.: Phys. Rev. B 82 174402 (2010). [2] S.K. Bose et al.: Phys. Rev. B 84 174442 (2011).