Enhanced weak superconductivity in trigonal γ-PtBi2.

Electrical resistivity experiments show superconductivity at Tc= 1.1 K in a high-quality single crystal of trigonal γ-PtBi2, with an enhanced critical magnetic field µ0Hc2(0) ≥ 1.5 Tesla and a low critical current-density Jc(0) ≈ 40 A/cm2 at H = 0. Both Tc and Hc2(0) are the highest reported values for stoichiometric bulk samples at zero pressure. We found a weak Hc2 anisotropy with Γ = Hab c2 /Hc c2 < 1, which is unusual among superconductors. Under a magnetic field, the superconducting transition becomes broader and asymmetric. Along with the low critical currents, this observation suggests an inhomogeneous superconducting state. In fact, no trace of superconductivity is observed through field-cooling-zero-field-cooling magnetization experiments.experiments.&#xD.