S. F. W. R. Rycroft

Shear-induced vortex decoupling in Bi 2 Sr 2 CaCu 2 O 8 crystals

Simultaneous transport and magnetization studies in

Current-induced decoupling of vortices in Bi2Sr2CaCu2O8

{\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}

Effect of surface barriers on transport properties of Bi2Sr2CaCu2O8 single crystals using the Corbino disc configuration

crystals at elevated currents reveal large discrepancies, including finite resistivity at temperatures of 40 K below the magnetic irreversibility line. This resistivity, measured at the top surface, is nonmonotonic in temperature and extremely nonlinear. The vortex velocity derived from magnetization is six orders of magnitude lower than the velocity derived from simultaneous transport measurements. The findings are ascribed to a shear-induced decoupling, in which the pancake vortices flow only in the top few

Current-enhanced anisotropy of Bi2Sr2CaCu2O8 in the mixed state

{\mathrm{CuO}}_{2}

Bulk transport properties of Bi 2 Sr 2 CaCu 2 O 8 crystals in the Corbino disk geometry

planes, and are decoupled from the pinned vortices in the rest of the crystal.

ROLE OF SAMPLE GEOMETRY ON NONLINEAR TRANSPORT PROPERTIES OF THE VORTEX SOLID IN BI2SR2CACU2O8

Abstract Simultaneous transport and magnetization measurements in Bi 2 Sr 2 CaCu 2 O 8 crystals are reported. The transport current is injected at the top surface, while Hall sensor arrays measure the local magnetic field across the crystals at the bottom. Surprisingly, at high-currents we find finite resistivity well below the magnetic irreversibility line, where the vortices are pinned . This resistivity is non-monotonic with temperature and highly non-linear. We interpret the new observation as a shear-induced decoupling, in which the vortices flow only in the top few layers and are decoupled from the pinned vortices in the rest of the crystal.

The effect of sample shape on the magnetisation in Bi2Sr2CaCu2O8+δ crystals

Transport measurements have been made on Bi2Sr2CaCu2O8 single crystals in both Corbino disc and strip geometries. Pronounced differences are observed in both the resistive transition and the current-voltage characteristics in these two geometries. Surface barriers affect the behaviour of the strip and reduce the measured resistance of the vortex liquid by over two orders of magnitude with respect to the Corbino geometry. The critical current density of the Corbino disc, which reflects the true bulk critical current, is a factor of at least 20 times smaller. We conclude that the transport properties of Bi2Sr2CaCu2O8 samples in the strip geometry are dominated by SB in both the solid and liquid vortex phases over a wide range of fields and temperatures.

Origin of linear extended defects in single crystalline Bi2Sr2CaCu2O8

Abstract Transport and local magnetization measurements carried out simultaneously in Bi 2 Sr 2 CaCu 2 O 8 (BSCCO) crystals reveal finite resistivity well below the magnetic irreversibility line, where the vortices should be pinned . This resistivity is non-monotonic with temperature and extremely non-linear. We describe the new observation in terms of a shear-induced decoupling, in which the pancake vortices flow only in the top few layers and are decoupled from the pinned vortices in the rest of the crystal.