Hysteretic loss vs. filament width in thin YBCO films near the penetration field

• Published in: IEEE transactions on applied superconductivity 2003-06, Vol.13 (2), p.3553-3556
• Main Authors: Sumption, M.D., Lee, E., Cobb, C.B., Barnes, P.N., Haugan, T.J., Tolliver, J., Oberly, C.E., Collings, E.W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Conductors; Electronics; Exact sciences and technology; Hysteresis; Laser ablation; Magnetic field measurement; Magnetometers; Microelectronic fabrication (materials and surfaces technology); Pulsed laser deposition; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Substrates; Superconducting devices; Temperature; Thin films; Transistors; Yttrium barium copper oxide
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2003.812396

Magnetization vs. applied field measurements (M-H loops) were taken on YBCO thin films with filaments patterned into them. The YBCO was deposited onto LaAlO/sub 3/ substrates using PLD, and the filaments were formed by laser ablation. M-H loops were taken at 4.2 K in fields up to /spl plusmn/9 T using a vibrating sample magnetometer technique, the field applied perpendicular to the film width, d. The losses were seen to be greatly reduced by filament width reductions following the standard expression Q/sub h//H/sub m/ /spl prop/ dJ/sub c//10. The penetration field was also well described by the standard "high field" expression H/sub p/ = (0.4J/sub c/t)ln(d/t + 1), where t is the film thickness. The regimes of applicability of the loss expression were investigated, in particular near H/sub m/ /spl ap/ H/sub p/. A more general form of the loss equation was obtained and compared with the high-field approximation. The result was that although Q/sub h//H/sub m/ still increased in proportion to d, the rate of increase decreased as H/sub m/ approached H/sub p/.