W. Göb

Double sign reversal of the vortex Hall effect in YBa 2 Cu 3 O 7 − δ thin films in the strong pinning limit of low magnetic fields

Measurements of the Hall effect and the resistivity in twinned

Interacting convection zones

{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}

Anomalous Hall effect and vortex pinning in high-Tc superconductors

thin films in magnetic fields B oriented parallel to the crystallographic c axis and to the twin boundaries reveal a double sign reversal of the Hall coefficient for

Hall-effect anomaly near T c and renormalized superconducting fluctuations in YBa 2 Cu 3 O 7¿x

Bl~1

Dynamics of photodoping and photoconductivity relaxation in oxygen-deficient YBa2Cu3Ox

T. In high transport current densities, or with B tilted off the twin boundaries by

Mixed-state Hall effect of YBa2Cu3O7 thin films at high current densities

5\ifmmode^\circ\else\textdegree\fi{},

Magnetic field and current density dependence of the mixed-state Hall effect in Bi2Sr2CaCu2Ox

the second sign reversal vanishes. The power-law scaling of the Hall conductivity to the longitudinal conductivity in the mixed state is strongly modified in the regime of the second sign reversal. Our observations are interpreted as strong, disorder-type dependent vortex pinning and confirm that the Hall conductivity in high-temperature superconductors is not independent of pinning.

Mixed-state Hall effect in high-temperature superconductors in small and large magnetic fields

Abstract 3D Numerical simulations of convection zones separated by a stable layer (according to the Schwarzschild criterion) are presented. The compressible case is considered. We make use of idealized microphysics closely related to polytropes. Decreasing the importance of the separating stable layer by diminishing its vertical extent in a series of models we investigate how the two convection zones merge into one. In our parameter range it is the upper zone which increases in size and ultimately squeezes the lower convection zone more or less out of existence. Properties of various fluxes and other physical quantities are discussed.

Anisotropic magnetoresistance in the normal state of oxygen-deficient YBa2Cu3O7-δ thin films induced by superconducting fluctuations

Abstract Pulsed high-current-density measurements of the Hall effect in the mixed state in several high- T c superconductors allow for a systematical tuning of the balance between Lorentz and pinning forces on the vortices. The characteristic temperatures for the single sign reversal in YBa 2 Cu 3 O 7− δ and those for the double sign change of the Hall effect in optimally-doped Bi 2 Sr 2 CaCu 2 O x are independent of current density. This confirms that the observed sign changes of the vortex Hall effect are intrinsic properties and are not evoked by vortex pinning. In contrast, underdoped Bi 2 Sr 2 CaCu 2 O x does not exhibit a sign reversal of the Hall effect but a negative contribution to the Hall conductivity can be detected when pinning is reduced in high-current densities.

Hall Anomaly Near Tc in YBa2Cu3O7-δ: Effects of Renormalized Superconducting Fluctuations and Pinning

Measurements of the Hall effect and the resistivity on precisely patterned