Laser scanning imaging and local characterization of superconducting properties in high-Tc thin film multiturn coil

Abstract

Low-temperature scanning laser microscopy has been used to investigate the spatial variation of the critical temperature Tc and critical current Ic in thin-film high-To multilayer structures that include dielectric layers. The method is described and measurements are presented on an YBa2Cu307_x-based multiturn coil with SrTiO3 insulating layer. We found that the critical temperature Tc of the YBa2Cu307_x tOp layer, from which the return strip of the coil is formed, is higher than that of the YBa2Cu307_x base layer. The critical current of the coil is limited by the quality of the YBa2Cu3OT_x base layer and not by the edges of the crossovers. 0921-4534/94/$07.00

Laser scanning microscopy of HTS films and devices (Review Article)

“…Similarly, a multi-turn thin-film antenna for a HTS SQUID was tested by the LSM in reference [48]. The device included the planar coil, the dielectric layer, the lead-out strip lying over the windings, and a protective STO layer.…”

“…This simple test can be successfully applied in other cases of quasi-1-D systems where the role of the temperature would be played by another parameter (magnetic field, beam modulation frequency, etc.) Similarly, a multi-turn thin-film antenna for a HTS SQUID was tested by the LSM in reference [48]. The device included the planar coil, the dielectric layer, the lead-out strip lying over the windings, and a protective STO layer.…”

Microwave Current Imaging in Passive HTS Components by Low-Temperature Laser Scanning Microscopy (LTLSM)

“…It is possible to manifest local resistive characterization of the SC transition [28][29][30], the spatial variations of magnetic and electromagnetic fields [31][32][33][34], and to carry out 2-D defectoscopy of structural and technological faults in operating SC devices and circuits [35][36][37]. In this work, we apply the LTLSM technique to analyze the redistribution of rf current flow in the vicinity of typical microdefects in YBCO films leading to anomalously high rf photoresponse, and possibly to nonlinear microwave behavior of SC devices.…”

Imaging the paramagnetic nonlinear Meissner effect in nodal gap superconductors

“…In such a way, only the ac component of the LSM PR is detected by a lock-in technique to enhance the signal-to-noise ratio and hence the contrast of the resulting images. A number of specific schemes for the LSM optics and electronics designed for the different detection modes have been published elsewhere [26,[50][51][52][53] and it is not a subject of discussion here.…”