Magneto-optical visualization of magnetic processes in superconducting strip with the application of magnetic fields and currents

The magneto-optical imaging (MOI) technique is widely employed to characterize the magnetic properties of superconductors and other magnetic materials because it can easily show the variation of flux density over a plane with relatively high resolution. In this paper, flux profiles visualized by the MOI technique will be presented for different experimental conditions. The sample investigated is a high-temperature superconducting single strip. Three cases are investigated: 1) application of external currents; 2) application of external magnetic fields; and 3) simultaneous application of external magnetic field and current. The behavior of complicated vortex penetration into the samples for different conditions will be discussed in detail. The magnetic flux profiles are calculated taking into account the sample thickness, as well as the interval between the sample and the MOI indicator film. The calculated and the experimental results are compared and discussed.