VISUALIZATION OF OPTICALLY CONTROLLED MAGNETIC-FLUX IN YBA2CU3O7-DELTA THIN-FILM LOOP BY TERAHERTZ RADIATION IMAGING

Magnetic flux generated optically in YBa2Cu3O7-delta thin film loops w as visualized by means of terahertz (THz) radiation imaging. By scanni ng the laser spot on the sample surface, we obtained a two-dimensional radiation pattern that represents supercurrent distribution. The obse rved images revealed that the fs laser pulse can create magnetic flux in the superconductive loops and also control the polarity of the flux . We discuss the relationship between the supercurrent distribution an d the optically generated magnetic flux in the loop.