In a layered superconductor, fluctuations of flux loops parallel to the layers result in destruction of the Josephson coupling between layers above a critical temperature Tf. When Fluctuations of point vortices in the layers are included, a 3-dimensional phase transition results at Tc<Tf. Study of this fluxon transition shows that variations of Tc as function of anisotropy can be much larger than those in an anisotropic XY model. This can account for the large variations of Tc in multilayers. Furthermore, the fluxon transition can be directly observed, corresponding to the onset of nonlinearity in the c axis I-V relation, as observed in Bi2Sr2CaCu2O8-y. This onset is at a higher temperature then the onset of nonlinearity in the ab plane.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering