Angle-resolvedI−Vcharacteristics measurements inBi1.8Pb0.2Sr2CaCu2O8+δsingle crystals with inclined columnar defects

Abstract

Current-voltage $(I\text{\ensuremath{-}}V)$ characteristics have been measured over a wide temperature range in a ${\mathrm{Bi}}_{1.8}{\mathrm{Pb}}_{0.2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ single crystal with tilted columnar defects (CDs). This configuration was compared to a crystal irradiated along the $c$ axis. Above $40\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and in the vortex solid state, angular measurements reveal a pronounced dip in the dissipation when a magnetic field is applied parallel to the CDs. At $T\ensuremath{\leqslant}40\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, the measured $I\text{\ensuremath{-}}V$ characteristics showed that besides the persistence of the directional pinning at low temperatures, there is a shift from the CDs toward the $c$ axis. Our samples showed, in the high temperature range $(T\ensuremath{\geqslant}40\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ and for ${B}_{\ensuremath{\phi}}∕10<\mathbf{H}<{B}_{\ensuremath{\phi}}$ (where ${B}_{\ensuremath{\phi}}$ is the matching field) applied parallel to the CDs, a three-dimensional Bose-glass transition with the same critical exponents as ${z}^{\ensuremath{'}}=5.3\ifmmode\pm\else\textpm\fi{}0.1$ and ${v}^{\ensuremath{'}}=1.1\ifmmode\pm\else\textpm\fi{}0.1$ which are in very good agreement with numerical simulations. Our findings support the existence of the Bose-glass-to-liquid transition at ${T}_{\mathrm{BG}}({\ensuremath{\mu}}_{0}H)$ in the case of tilted columnar defects.