Vortex dynamics in La_1.86Sr_{0. 14}CuO₄studied by magnetoresistivity

Abstract Vortex dynamics in La1.86Sr0.14CuO4 have been studied by the measurement of ρc //i (T, H), where ρc //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 ρc //a-b (T, H) data onto the corresponding ρc //c (T, H) curves. This scaling property clearly indicates that the Lorentz-force-free mechanism is responsible for ρc //a-b (T, H). Furthermore, we also show that the measured ρc //a-b (T, H) data can be explained in terms of the recently developed extended Josephson coupling model which is verified by rescaling ρc //a-b (T) data for various fields onto a single curve.