RAPID COMMUNICATION: Superconductivity at 53.5 K in GdFeAsO1-δ

Here we report the fabrication and superconductivity of the iron-based arsenic oxide GdFeAsO_1-δ compound with oxygen-deficiency, which has an onset resistivity transition temperature at 53.5 K. This material has the same crystal structure as the newly discovered high-T_c ReFeAsO_1-δ family (Re = rare earth metal) and a further reduced crystal lattice, while the T_c starts to decrease compared with the SmFeAsO_1-δ system.