Superconductivity in epitaxial La_2-xPt_xSi films

In noncentrosymmetric superconductors, by doping with heavy-elements, the absence of inversion symmetry and presence of parity-violating antisymmetric spin-orbit coupling may lead to admixture of spin-singlet and spin-triplet components. We investigated the transport properties of various La_2-xPt_xSi thin films grown by molecular beam epitaxy (MBE). The Pt doping suppresses transition temperatures, and tunes the charge carrier types and densities dramatically. Interestingly, the magnetoresistance shows a two-step transition at finite temperatures below T_c. Furthermore, the differential resistance measurement reveals complex superconducting gap structures in magnetic fields up to 1 T. These features indicate the competing orders in the materials.