Anisotropic in-plane reversible strain effect in Y0.5Gd0.5Ba2Cu3O7−δ coated conductors

Recent experiments have shown that reversible effects of strain on the critical current density and flux pinning strength in the high-temperature superconductor Bi2Sr2Ca2Cu3Ox can be explained entirely by the pressure dependence of its critical temperature. Such a correlation is less simple for RE–Ba2Cu3O7−δ (RE = rare earth) superconductors, in part because the in-plane pressure dependence of its critical temperature is highly anisotropic. Here, we make a qualitative correlation between the uniaxial pressure dependence of the critical temperature and the reversible strain effect on the critical current of RE–Ba2Cu3O7−δ coated conductors by taking the crystallography and texture of the superconducting film into account. The strain sensitivity of the critical current is highest when strain is oriented along the [100] and [010] directions of the superconducting film, whereas the critical current becomes almost independent of strain when strain is oriented along the [110] direction. The results confirm the important role of the anisotropic pressure dependence of the critical temperature on the reversible strain behavior of RE–Ba2Cu3O7−δ. The reversible strain effect in RE–Ba2Cu3O7−δ is expected to decrease the performance of the conductor in many applications, such as high-field magnets, but the effect may be only minor in coated conductor cables, where strain is generally not aligned with the tape axis.