We have investigated the depinning process of magnetic flux vortices in twinned crystals of YBa2Cu3O7-δ in intermediate applied magnetic fields parallel to the crystallographic c axis through precise resistivity measurements before and after fast-neutron irradiation. Of particular interest for each field is the power-law dependence of the electric field on current density, E∝Jn, at a well defined temperature which separates a nonlinear region below from a more linear, dissipative region above. We find that n shows a striking dependence on the estimated value of the Larkin-Ovchinnikov length. The relation is not only manifest before and after irradiation but also for a variety of samples, including films, crystals, and at least two copper oxides other than YBa2Cu3O7-δ.
Brown, Brandon R., "Neutron-irradiation Effects on the V-I Characteristics of YBa2Cu3O7-δ Twinned Crystals:Linking Transport Results in a Variety of Copper Oxide Superconductors" (1997). Physics and Astronomy. Paper 22.