Split Fermi Surface Properties in Ullmannite NiSbS and PdBiSe with the Cubic Chiral Crystal Structure

We grew single crystals of ullmannite NiSbS and PbBiSe with the cubic chiral structure and carried out electrical resistivity, specific heat, and de Haas-van Alphen (dHvA) experiments to clarify their Fermi surface properties. The Fermi surfaces were found to split into two, reflecting the non-centrosymmetric crystal structure. The splitting energies between the two nearly spherical electron Fermi surfaces named alpha and alpha' were determined as 220K in NiSbS and 1050K in PdBiSe for H parallel to [100] or [001]. This difference in splitting energies between the two compounds originates mainly from the fact that the spin-orbit interactions of Ni-3d, Sb-5p, and S-3p electrons in NiSbS are smaller in magnitude than those of Pd-4d, Bi-6p, and Se-4p electrons in PdBiSe, respectively.