The reversible strain effect on critical current over a wide range of temperatures and magnetic fields for YBCO coated conductors

• Published in: Superconductor science & technology Vol. 23; no. 8; p. 085013
• Main Authors: Sugano, Michinaka, Shikimachi, Kouji, Hirano, Naoki, Nagaya, Shigeo
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.08.2010; Institute of Physics
• Subjects: BOUNDARIES; COMPRESSIVE PROPERTIES; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductors; COPPER OXIDE; Critical currents; Exact sciences and technology; Flux pinning; GRAIN BOUNDARIES; Grains; High-tc films; MAGNETIC FIELD; Magnetic fields; Physics; PINNING; PROPERTIES; Properties of type I and type II superconductors; STRAIN; Superconducting films and low-dimensional structures; Superconductivity; SUPERCONDUCTORS; Vortex lattices ,flux pinning, flux creep; YBCO superconductors; YTTRIUM OXIDE; Grain boundaries; Strain rate sensitivity; Magnetic field effects; Low field; Compressive stress; Tensile stress; Flux pinning; Critical current; Temperature effects; High-Tc superconductors; Coated conductor; Uniaxial strain; Stress effects; Barium Copper Yttrium Oxides Mixed; Thermal stresses
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/23/8/085013

The strain effect on critical current (Ic( Delta *e)) in Y Ba2Cu3O7 - Delta *d (YBCO) coated conductors was evaluated at temperatures in the range 20--83 K under magnetic fields parallel to the c-axis up to 10 T. The peaked reversible variation of Ic with applied uniaxial strain was confirmed in the self-field at all tested temperatures. The strain sensitivity increases with increasing temperature, resulting in a more pronounced reversible suppression with strain at higher temperature. Interestingly, it was found that the peak strain corresponding to the maximum of Ic shifts to the compressive side with decreasing temperature. Such a peak shift cannot be explained by a change in the thermal residual strain of the YBCO film, suggesting that the peak strain of the Ic( Delta *e) in YBCO coated conductors is not determined only by relaxation of the residual strain. The strain sensitivity of Ic( Delta *e) at 60 K becomes greater with increasing magnetic field, while the influence of the magnetic field is much less pronounced at 20 K. The in-field Ic( Delta *e), including the compressive strain region as well as the tensile region, shows a double peak behavior at low magnetic field at 77 and 83 K. The temperature and magnetic field effect on Ic( Delta *e) in YBCO coated conductors is discussed considering flux pinning within the grains and on grain boundaries.