Free electron laser-induced photocurrent in high-Tc superconducting YBa2Cu3O7−x films

Abstract We investigate the high-temperature YBa 2 Cu 3 O 7− x superconductors by method using a free electron laser (FEL). The method is a type of photoelectron spectroscopy and called a FEL internal photoemission. It is found that when the YBa 2 Cu 3 O 7− x film is irradiated by FEL, the photocurrent is induced in an unbias condition.