Josephson vortices at tricrystal boundaries

Abstract

Josephson vortices at tricrystal boundaries with and without a (Formula presented) junction in zero applied field are considered. It is shown that if the three tricrystal arms are conventional junctions, a one-flux-quantum (Formula presented) vortex at or near the intersection has lower energy than one far from the intersection. If the largest Josephson length exceeds the sum of the other two, the tricrystal ceases to be a pinning site. If one of the tricrystal arms is a (Formula presented) junction, a (Formula presented) vortex at the intersection is the ground state of the system, and an even number of (Formula presented) vortices is forbidden, whereas (Formula presented) and (Formula presented) correspond to possible but, in general, metastable states. For certain combinations of Josephson lengths, the (Formula presented) state has lower energy than the combined energy of the (Formula presented) vortex at the tricrystal joint and a (Formula presented) vortex far from the joint. Conditions are discussed under which the (Formula presented) vortex can be observed. © 2000 The American Physical Society.