Effect of strain, magnetic field and field angle on the critical current density ofY Ba2Cu3O7−δ coated conductors**Contribution of NIST, not subject to US copyright.

Abstract

A large, magnetic-field-dependent, reversible reduction in critical current density with axial strain inY Ba2Cu3O7−δ coatedconductors at 75.9 K has been measured. This effect may have important implications for the performanceof Y Ba2Cu3O7−δ coated conductors in applications where the conductor experiences large stresses in thepresence of a magnetic field. Previous studies have been performed only under tensile strainand could provide only a limited understanding of the in-field strain effect. Wenow have constructed a device for measuring the critical current density as afunction of axial compressive and tensile strain and applied magnetic field aswell as magnetic field angle, in order to determine the magnitude of this effectand to create a better understanding of its origin. The reversible reduction incritical current density with strain becomes larger with increasing magnetic field atall field angles. At 76 K the critical current density is reduced by about 30% at − 0.5% strain when a magnetic field of 5 T is applied parallel to thec-axis of the conductor or 8 T is applied in theab-plane, compared to a reduction of only 13% in self-field. Differences in the strain response of thecritical current density at various magnetic field angles indicate that the pinning mechanisms inY Ba2Cu3O7−δ coated conductors are uniquely affected by strain.