Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 26: Skyrmions I (joint session MA/KFM/TT)

TT 26.12: Vortrag

Montag, 12. März 2018, 18:15–18:30, EB 301

Spin-orbit coupling effects in magnetic and response properties of B20 A_1−xB_xGe alloys (A, B = Mn, Fe, Co, Rh) — •Sergiy Mankovsky¹, Sebastian Wimmer¹, Svitlana Polesya¹, Nicolas Martin², Isabelle Mirebeau², and Hubert Ebert¹ — ¹Dept. Chemistry, LMU Munich, D-81377 Munich, Germany — ²Lab. Léon Brillouin, CEA, CNRS, Uni. Paris-Saclay, France

The composition-dependence of the isotropic exchange (J_ij) and Dzyaloshinskii-Moriya interaction (DMI) (D_ij^→) of Mn_1−xFe_xGe, Mn_1−xRh_xGe, Mn_1−xCo_xGe and Fe_1−xCo_xGe B20 alloys have been investigated by first-principles calculations using the relativistic multiple scattering Korringa-Kohn-Rostoker (KKR) formalism. The D^αα (α = x, y, z) elements of the DMI tensor exhibit a strong dependence on the composition, changing sign at x ≈ 0.85 in Mn_1−xFe_xGe and at x ≈ 0.5 in Fe_1−xCo_xGe, in line with previous theoretical calculations as well as with experimental results. The spin-orbit torque (SOT), anomalous and spin Hall conductivities (AHC and SHC, respectively) of Mn_1−xFe_xGe alloys have been investigated. A sign change at x ≈ 0.5 is predicted for the Fermi sea contribution to the SOT, as this is closely related to the DMI. In the case of anomalous and spin Hall effects it is shown that the calculated Fermi sea contributions are rather small and the composition-dependence of these effects are determined mainly by the electronic states at the Fermi level. The spin-orbit-induced scattering mechanisms responsible for both effects are suggested to cause the minimum of the AHC and the sign change of the SHC.