Split Fermi Surface Properties of LaTGe3 (T: Transition Metal) and PrCoGe3 with the Non-centrosymmetric Crystal Structure

Abstract

We succeeded in growing single crystals of LaTGe 3 (T: Fe, Co, Rh, Ir) and PrCoGe 3 with the non-centrosymmetric tetragonal crystal structure, and studied the split Fermi surface properties and the magnitude of the antisymmetric spin–orbit interaction 2|α p ⊥ |. The 2|α p ⊥ | value is found to vary when LaTGe 3 is changed from T = Co, Rh to Ir, but remains unchanged in LaIrX 3 from X = Si to Ge. It is found that this 2|α p ⊥ | value is large in LaIrSi 3 and LaIrGe 3 : 2|α p ⊥ | = 460 K in LaCoGe 3 , 510 K in LaRhGe 3 , 1100 K in LaIrSi 3 , and 1090 K in LaIrGe 3 for the main outer orbits named α of bands 69 and 70 electron Fermi surfaces, for example. This is due to the large effective atomic number of Ir and a large distribution of the radial wave function of Ir-5 d electrons close to the nuclear center, compared with those of Co and Rh. In the case of a paramagnet PrCoGe 3 and LaFeGe 3 with the relatively large cyclotron mass, the corresponding 2|α p ⊥ | value is found to become small: 2|α p ⊥ | = 280 a...