Investigation of phase-slip-like resistivity in underdoped YBCO

We investigated the anomalous peak resistivity below the onset $T_c$ in underdoped YBCO, reminiscent of that observed in 1D wires of conventional superconductors. We performed measurements of the angular dependence of resistivity $\rho(\theta)$ in a magnetic field and the temperature dependence of resistivity $\rho(T)$, which exhibit a peak for $\textbf{B} \parallel$ ab-planes. This peak in $\rho(T)$ disappears for $\textbf{B} \parallel$ c-axis. The width of the corresponding maximum in $\rho(\theta)$ at $\theta=0^o$ ($\textbf{B} \parallel$ ab-planes) decreases with increasing c-axis component of the field ($B \sin \theta$). The maximum in $\rho(\theta)$ and $\rho(T)$ decreases with an increasing applied transport current. We analyzed the data using three different models of resistivity based on 2D resistor array, flux motion, and thermally activated phase-slips. Numerical calculations suggest that in a filamentary underdoped system, the phase-slip events could produce the anomalous resistivity close to $T_c$.