Magnetic and superconducting properties of CeTX3 (T: transition metal and X: Si and Ge) with non-centrosymmetric crystal structure

We grew single crystals of non-centrosymmetric compounds CeTSi3 and CeTGe3 (T: transition metal), and studied the magnetic properties by measuring the electrical resistivity, magnetic susceptibility and magnetization. We also studied the effect of pressure on the electronic states in antiferromagnets CeTGe3 (T: Co, Rh, Ir) by measuring the resistivity under pressure. No noticeable change of the Neel temperature was observed up to 8 GPa in CeRhGe3, and CeIrGe3, which are far from the magnetic quantum critical point. On the other hand, the Neel temperature in CeCoGe3 was strongly decreased as a function of pressure, and pressure-induced superconductivity was observed in the pressure region from 5.4 GPa to about 7.5 GPa. The slope of upper critical field Hc2 at 6.5 GPa is found to be extremely large, with an upturn curvature of Hc2 with decreasing temperature: -dHc2/dT=200kOe/K at the superconducting transition temperature Tsc=0.69K, revealing unconventional superconductivity. (author)