2 research outputs found
Charge-Vortex Duality in Double-Layered Josephson Junction Arrays
A system of two parallel Josephson junction arrays coupled by interlayer
capacitances is considered in the situation where one layer is in the
vortex-dominated and the other in the charge-dominated regime. This system
shows a symmetry (duality) of the relevant degrees of freedom, i.e. the
vortices in one layer and the charges in the other. In contrast to single-layer
arrays both contribute to the kinetic energy. The charges feel the magnetic
field created by vortices, and, vice versa, the vortices feel a gauge field
created by charges. For long-range interaction of the charges the system
exhibits two Berezinskii-Kosterlitz-Thouless transitions, one for vortices and
another one for charges. The interlayer capacitance suppresses both transition
temperatures. The charge-unbinding transition is suppressed already for
relatively weak coupling, while the vortex-unbinding transition is more robust.
The shift of the transition temperature for vortices is calculated in the
quasi-classical approximation for arbitrary relations between the capacitances
(both weak and strong coupling).Comment: 12 pages, Revtex 3.
Nature of the Low Field Transition in the Mixed State of High Temperature Superconductors
We have numerically studied the statics and dynamics of a model
three-dimensional vortex lattice at low magnetic fields. For the statics we use
a frustrated 3D XY model on a stacked triangular lattice. We model the dynamics
as a coupled network of overdamped resistively-shunted Josephson junctions with
Langevin noise. At low fields, there is a weakly first-order phase transition,
at which the vortex lattice melts into a line liquid. Phase coherence parallel
to the field persists until a sharp crossover, conceivably a phase transition,
near which develops at the same temperature as an infinite
vortex tangle. The calculated flux flow resistivity in various geometries near
closely resembles experiment. The local density of field induced
vortices increases sharply near , corresponding to the experimentally
observed magnetization jump. We discuss the nature of a possible transition or
crossover at (B) which is distinct from flux lattice melting.Comment: Updated references. 46 pages including low quality 25 eps figures.
Contact [email protected] or visit
http://www.physics.ohio-state.edu:80/~ryu/ for better figures and additional
movie files from simulations. To be published in Physical Review B1 01Jun9