Enhanced weak superconductivity in trigonal γ-PtBi₂

Electrical resistivity experiments show superconductivity atTc=1.1K in a high-quality single crystal of trigonalγ-PtBi₂, with an enhanced critical magnetic fieldμ0Hc2(0)≳1.5Tesla and a low critical current-densityJc(0)≈40 A cm^-2atH = 0. BothT_candHc2(0)are the highest reported values for stoichiometric bulk samples at ambient pressure. We found a weakHc2anisotropy withΓ=Hc2ab/Hc2c<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.