Vortex lattice melting and Hc 2 in underdoped YBa

Josephson Plasma Resonance in Solid and Glass Phases of Bi 2 Sr 2 Cacu 2 O 8+δ

Vortex matter phases and phase transitions are investigated by means of Josephson plasma resonance in underdoped Bi2Sr2CaCu2O8+δ single crystals in a microwave frequency range between 19 and 70 GHz. Accompanied by the vortex lattice melting transition, a jump of the interlayer phase coherence extracted from the field dependence of the plasma frequency was observed. In the solid phase, the inter...

Crossover from 2 D to 3 D behavior in the superfluid density of thin YBa 2 Cu 3 O 7 d films

Ultrathin underdoped films of YBa2Cu3O7 d (YBCO) exhibit a prominent and abrupt downturn in ab-plane superfluid density nS(T) at a temperature consistent with a 2D vortex-pair unbinding transition. In this paper, we show that this characteristic feature of 2D superconductors diminishes with increasing film thickness consistent with theory, provided one uses the full film thickness rather than a...

A ug 1 99 9 First order phase transition of the vortex lattice in twinned YBa 2 Cu 3 O 7 single crystals in tilted magnetic fields

Fluctuations in the Josephson–pancake combined vortex lattice

We study vortex fluctuations in strongly anisotropic layered superconductors placed in tilted magnetic fields where there are two alignments of vortices: pancake vortices (PV s) oriented along the c-axis, and Josephson vortices (JV s) aligned along the ab-plane. For low enough out-of-plane magnetic fields Hc, the JV sublattice pins some PV s, confining several of their degrees of freedom. This ...

Vortex liquid correlations induced by in-plane field in underdoped Bi2Sr2CaCu2O8+δ

By measuring the Josephson Plasma Resonance, we have probed the influence of an in-plane magnetic field on the pancake vortex correlations along the c-axis in heavily underdoped Bi2Sr2CaCu2O8+δ (Tc = 72.4 ± 0.6 K) single crystals both in the vortex liquid and in the vortex solid phase. Whereas the in-plane field enhances the interlayer phase coherence in the liquid state close to the melting li...