Synthesis and physical properties of the theoretically predicted spin-triplet superconductor Li0.9Mo6O17

Abstract

We report the single crystal growth and characterization of the quasi-one-dimensional superconductor Li0.9Mo6O17 via temperature-gradient flux method. The grown single crystals show a clear ab plane identified by the x-ray diffraction (XRD) pattern. Temperature dependent resistivities reveal a metallic to semiconducting crossover at TM= 24 K followed by a superconducting transition at Tc= 2.2 K for ρa and ρc. In addition, the upper critical fields demonstrate a large anisotropy with Hc2b>Hc2a>Hc2c both at ρa and ρc. Particularly, an upper critical field Hc2b of about 16.2 T at zero temperature limit was deduced from the field dependence of resistivity measurements, which is notably larger than the estimated Pauli paramagnetic limit 3.1 T and supports the existence of the spin-triplet superconducting pairing and unconventional superconductivity in Li0.9Mo6O17. The XRD, resistivities and upper critical field measurements all imply a high quality of the as-grown Li0.9Mo6O17 samples. Furthermore, the interlayer and in-plane magnetoresistivity (MR) up to 60 T reveal the possible phase transition driven by the density-wave gap suppression and Zeeman split effect in the high field state.