Anisotropic Hc2, thermodynamic and transport measurements, and pressure dependence of Tc in K2Cr3As3 single crystals

We present a detailed study of single crystalline K2Cr3As3 and analyze its thermodynamic and transport properties, anisotropic H-c2(T), and initial pressure dependence of T-c. In zero field, the temperature-dependent resistivity is metallic. Deviation from a linear temperature dependence is evident below100Kand a T-3 dependence is roughly followed from just above T-c (similar to 10 K) to similar to 40 K. Anisotropic H-c2(T) data were measured up to 140 kOe with field applied along and perpendicular to the rodlike crystals. For the applied field perpendicular to the rod, H-c2(T) is linear with a slope similar to-70 kOe/K. For field applied along the rod, the slope is about -120 kOe/K below 70 kOe. Above 70 kOe, the magnitude of the slope decreases to similar to-70 kOe/K. The electronic specific heat coefficient gamma, just above T-c, is 73 mJ/mol K-2; the Debye temperature Theta(D) is 220 K. The specific heat jump at the superconducting transition Delta C similar to 2.2 gamma T-c. Finally, for hydrostatic pressures up to similar to 7 kbar, T-c decreases under pressure linearly at a rate of -0.034K/kbar.