title: Oscillatory melting temperature of the vortex smectic phase in layered superconductors
abstract: We report on transport measurements of YBa 2Cu 3O (7-delta) single crystals with different oxygen contents in the geometry B, J ||ab (J perpendicularB). Our data show that the vortices become confined between the Cu-O planes below a well-defined temperature at which the effective size 2xi of the vortex core is approximately equal to the period of the Cu-O layers. This confinement strongly increases the vortex liquid freezing temperature. A new melting line is found separating a vortex liquid and a smectic phase, which shows an oscillatory field dependence reflecting differences between commensurate and incommensurate smectic states.
authors.affiliation: Department of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
authors.initials: SN
authors.lastname: Gordeev
authors.initials: AA
authors.lastname: Zhukov
authors.lastname: de Groot PA
authors.initials: AG
authors.lastname: Jansen
authors.initials: R
authors.lastname: Gagnon
authors.initials: L
authors.lastname: Taillefer