Onset of the Meissner effect at 65 K in FeSe thin film grown on Nb-doped SrTiO3 substrate

We report the Meissner effect studies on an FeSe thin film grown on Nb-doped SrTiO3 substrate by molecular beam epitaxy. Two-coil mutual inductance measurement clearly demonstrates the onset of diamagnetic screening at 65 K, which is consistent with the gap opening temperature determined by previous angle-resolved photoemission spectroscopy results. The applied magnetic field causes a broadening of the superconducting transition near the onset temperature, which is the typical behavior for quasi-two-dimensional superconductors. Our results provide direct evidence that FeSe thin film grown on Nb-doped SrTiO3 substrate has an onset T-C similar to 65 K, which is the highest among all iron-based superconductors discovered so far.