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

Abstract

The strain effect on critical current(Ic(ε)) inY Ba2Cu3O7 − δ (YBCO)coated conductors was evaluated at temperatures in the range 20–83 K under magnetic fields parallel tothe c-axis up to 10 T. The peaked reversible variation ofIc with applied uniaxial strain was confirmed in the self-field at all tested temperatures.The strain sensitivity increases with increasing temperature, resulting in amore pronounced reversible suppression with strain at higher temperature.Interestingly, it was found that the peak strain corresponding to the maximum ofIc shifts to the compressive side with decreasing temperature. Such a peak shift cannot be explainedby a change in the thermal residual strain of the YBCO film, suggesting that the peak strain of theIc(ε) inYBCO coated conductors is not determined only by relaxation of the residual strain. The strain sensitivityof Ic(ε) at 60 K becomes greater with increasing magnetic field, while the influenceof the magnetic field is much less pronounced at 20 K. The in-fieldIc(ε), including the compressive strain region as well as the tensile region, shows a double peakbehavior at low magnetic field at 77 and 83 K. The temperature and magnetic field effect onIc(ε) in YBCO coated conductors is discussed considering flux pinning within the grains and ongrain boundaries.