Split Fermi Surface Properties of Noncentrosymmetric Compounds Fe2P, Ni2P, and Pd2Si

We grew single crystals of Fe2P, Ni2P, and Pd2Si with a noncentrosymmetric Fe2P-type hexagonal structure, studied their Fermi surface properties by de Haas-van Alphen (dHvA) experiments, and compared results with energy band calculations. In paramagnets Ni2P and Pd2Si, the detected dHvA branches are well explained by the results of full potential linear augmented plane wave (FLAPW) band calculations. Because of the noncentrosymmetric crystal structure, the energy band splits, leading to two split Fermi surfaces. The angular dependences of dHvA frequencies for the main split Fermi surfaces are highly anisotropic, which is not observed for H parallel to [0001] but observed for H perpendicular to [0001]. The splitting energy due to the antisymmetric spin orbit coupling is approximately estimated to be Delta epsilon similar or equal to 300 K in Ni2P and 500K in Pd2Si for H parallel to [10 (1) over bar0]. This is a characteristic feature of the split Fermi surfaces in these compounds. In the case of a ferromagnet Fe2P, only one kind of spin-split dHvA branch was observed.