Visualization of Optically Controlled Magnetic Flux in YBa₂Cu₃O_7-δ Thin Film Loop by Terahertz Radiation Imaging

Abstract

Magnetic flux generated optically in YBa 2 Cu 3 O 7-δ thin film loops was visualized by means of terahertz (THz) radiation imaging. By scanning the laser spot on the sample surface, we obtained a two-dimensional radiation pattern that represents supercurrent distribution. The observed 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 and the optically generated magnetic flux in the loop.