Split Fermi surface properties of LaTGe3 (T:transition metal) and PrCoGe3 with the non-centrosymmetric crystal structure

We succeeded in growing single crystals of LaTGe3 (T: Fe, Co, Rh, Ir) and PrCoGe3 with the non-centrosymmetric tetragonal crystal structure, and studied the split Fermi surface properties and the magnitude of the antisymmetric spin-orbit interaction 2 vertical bar alpha p perpendicular to vertical bar. The 2 vertical bar alpha p perpendicular to vertical bar value is found to vary when LaTGe3 is changed from T = Co, Rh to Ir, but remains unchanged in LaIrX3 from X = Si to Ge. It is found that this 2 vertical bar alpha p perpendicular to vertical bar value is large in LaIrSi3 and LaIrGe3: 2 vertical bar alpha p perpendicular to vertical bar = 460 K in LaCoGe3, 510 K in LaRhGe3, 1100 K in LaIrSi3, and 1090 K in LaIrGe3 for the main outer orbits named alpha 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-5d electrons close to the nuclear center, compared with those of Co and Rh. In the case of a paramagnet PrCoGe3 and LaFeGe3 with the relatively large cyclotron mass, the corresponding 2 vertical bar alpha p perpendicular to vertical bar value is found to become small: 2 vertical bar alpha p perpendicular to vertical bar= 280 and 460 K for main orbits ot in PrCoGe3 and LaCoGe3, respectively, and 130 K for main orbits in LaFeGe3.