Vortex dynamics in La_1.86Sr_{0. 14}CuO₄ studied by magnetoresistivity

Abstract

Vortex dynamics in La_1.86Sr_0.14CuO₄ have been studied by the measurement of ρ_c ^//i (T, H), where ρ_c ^//i is the c-axis resistivity for H//i (i = c or a-b). We argue that, at temperatures higher than the irreversibility temperature T _irr, the usual vortex picture breaks down owing to the thermal motion of vortices, resulting in a T- and T _in-dependent anisotropic parameter γ. After taking into account the dependence of γ on T and T _irr, we show that at each given temperature we can rescale the ρ_c ^//a-b (T, H) data onto the corresponding ρ_c ^//c (T, H) curves. This scaling property clearly indicates that the Lorentz-force-free mechanism is responsible for ρ_c ^//a-b (T, H). Furthermore, we also show that the measured ρ_c ^//a-b (T, H) data can be explained in terms of the recently developed extended Josephson coupling model which is verified by rescaling ρ_c ^//a-b (T) data for various fields onto a single curve.