Flux Lattice Melting and Dimensional Crossover in Bi-2212 Single Crystals

First Order Transitionof Thevortex Lattice in Disordered Bi-2212 Crystals

Using differential magneto-optical imaging, we address the question of mesoscopic inhomogeneity in underdoped Bi2Sr2CaCu2O8 (Bi-2212) single crystals. Among other features, it is shown that an anomalous temperature dependence of the penetration field and of the first order transition (FOT) field of the vortex lattice in such crystals can be understood as arising from inhomogeneity. The effect o...

Dimensional Crossover of Vortex Dynamics Induced by Gd Substitution on Bi 2212 Single Crystals ⋆

The vortex dynamics of Bi2Sr2Ca1−xGdxCu2O8+δ single crystals is investigated by magnetic relaxation and hysteresis measurements. By substituting Ca with Gd, it is found that the interlayer Josephson coupling is weakened and the anisotropy is increased, which leads to the change of vortex dynamics from 3D elastic to 2D plastic vortex creep. Moreover, the second magnetization peak, which can be o...

Superconductivity and flux pinning in Y and heavily Pb codoped Bi-2212 single crystals

co nd - m at / 9 90 32 32 15 M ar 1 99 9 - 1 - Evidence for a Two - stage Melting Transition of the Vortex Matter in

From muon spin rotation measurements on under-to overdoped Bi-2212 crystals we obtain evidence for a two-stage transition of the vortex matter as a function of temperature. The first transition is well known and related to the irreversibility line (IL). The second one is located below the IL and has not been previously observed. It occurs for all three sets of crystals and is unrelated to the v...

Reentrant peak effect and the melting of a flux line lattice in 2H-NbSe2.

A reentrant peak effect is observed through low field ac susceptibility measurements on the weakly pinned flux line lattice in single crystals of 2H-NbSe2. The resulting phase diagram of the peak effect is strikingly similar to the theoretically predicted reentrant phase boundary which separates flux lattice and flux liquid phases. The broadening and ultimate disappearance of the peak effect at...