Oscillatory melting temperature of the vortex smectic phase in layered superconductors
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.
Gordeev
SN
Department of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
Zhukov
AA
de Groot PA
Jansen
AG
Gagnon
R
Taillefer
L