In-plane angular magnetoresistivity $\Delta {\rho }_{ab}^{\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{s}}$ measurements were made on ${\mathrm{Y}}_{1-x}\mathrm{P}{\mathrm{r}}_x\mathrm{B}{\mathrm{a}}_2\mathrm{C}{\mathrm{u}}_3{\mathrm{O}}_{7-\delta }$ single crystals in the pseudogap region. For $x\ge 0.2$ single crystals, $\Delta {\rho }_{ab}^{\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{s}}(\theta )$ displays a deviation from the typical quasiparticle contribution ($\propto {sin}^2\theta$) for temperatures smaller than a certain value $T_{\varphi }$ in the pseudogap region. This deviation is consistent with a flux-flow type contribution to angular magnetoresistivity, indicating the presence of vortexlike excitations above the zero-field critical temperature in the pseudogap region.

• Received 12 August 2003

DOI:https://doi.org/10.1103/PhysRevLett.93.177005