Vortex fractionalization in a Josephson ladder
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Publisher:American Physical Society
Citation:I. Tornes, D. Stroud, "Vortex fractionalization in a Josephson ladder," Physical Review B 72, no. 22 (2005), doi:10.1103/PhysRevB.72.224519
We show numerically that, in a Josephson ladder with periodic boundary conditions and subject to a suitable transverse magnetic field, a vortex excitation can spontaneously breakup into two or more fractional excitations. If the ladder has N plaquettes, and N is divisible by an integer q, then in an applied transverse field of 1∕q flux quanta per plaquette the ground state is a regular pattern of one fluxon every q plaquettes. When one additional fluxon is added to the ladder, it breaks up into q fractional fluxons, each carrying 1∕q units of vorticity. The fractional fluxons are basically walls between different domains of the ground state of the underlying 1∕q lattice. The fractional fluxons are all depinned at the same applied current and move as a unit. For certain applied fields and ladder lengths, we show that there are isolated fractional fluxons. It is shown that the fractional fluxons would produce a time-averaged voltage related in a characteristic way to the ac voltage frequency.
Rights:©2005 The American Physical Society
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