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要旨:
We address the electron transport characteristics in bulk half-Heusler
alloys with their compositions tuned to the borderline between
topologically nontrivial semimetallic and trivial semiconducting phases.
Accurate first-principles calculations based on the coherent potential
approximation (CPA) reveal that all the studied systems exhibit sets of
dispersionless impurity-like resonant levels, with one of them being
located at the Dirac point. By means of the Kubo-Bastin formalism we
reveal that the residual conductivity of these alloys is strongly
suppressed by impurity scattering, whereas the spin Hall conductivity
exhibits a rather complex behavior induced by the resonant states. In
particular for LaPt0.5Pd0.5Bi we find that the total spin Hall
conductivity is strongly suppressed by two large and opposite
contributions: the negative Fermi-surface contribution produced by the
resonant impurity and the positive Fermi-sea term stemming from the
occupied states. At the same time, we identify no conductivity
contributions from the conical states.
