Speaker: Eundeok Mun, SFU

Time: 10:00-11:00am

Location: BRIM 311

Title: Interplay between metal-to-Insulator-like transition and superconductivity in Ga-doped Re₃Ge₇ single crystals

Abstract: Growing single crystals of Re₃Ge₇ allows for detailed investigations into its complex electronic behavior, revealing it as a material with an emerging unconventional charge ordered state and superconductivity by external pressure and doping. To further explore characteristics, we have synthesized single crystals of Ga-doped Re₃Ge₇ and performed magnetization, electrical resistivity, specific heat, and thermoelectric power measurements. In this talk I will share new findings in this system. The obtained x-T phase diagram of Re₃(Ga_xGe_1-x)₇ exhibits a close relationship between metal-to-insulator-like (MIL) transition and superconducting transition temperature. Interestingly, superconductivity emerges when the MIL transition becomes a maximum and the maximum superconducting transition temperature can be achieved when the MIL transition is suppressed, basically forming a superconducting dome. The upper critical field (H_c2) measurements exhibit that H_c2 curves are well described by the Ginzburg-Landau equation in the right side of the superconducting dome. On the other hand, the H_c2 curve in the left side of the dome deviates from the Ginzburg-Landau model at low temperatures, where the superconductivity and MIL transition coexists. Furthermore, samples showing superconductivity indicate a re-entrance of zero-resistance state (peak effect) under external magnetic field, providing a good opportunity to study complex vortex state.