Oscillatory eigenmodes and stability of one and two arbitrary fractional vortices in long Josephson 0-kappa-junctions

Abstract

We investigate theoretically the eigenmodes and the stability of one and two arbitrary fractional vortices pinned at one and two $\kappa$-phase discontinuities in a long Josephson junction. In the particular case of a single $\kappa$-discontinuity, a vortex is spontaneously created and pinned at the boundary between the 0 and $\kappa$-regions. In this work we show that only two of four possible vortices are stable. A single vortex has an oscillatory eigenmode with a frequency within the plasma gap. We calculate this eigenfrequency as a function of the fractional flux carried by a vortex. For the case of two vortices, pinned at two $\kappa$-discontinuities situated at some distance $a$ from each other, splitting of the eigenfrequencies occur. We calculate this splitting numerically as a function of $a$ for different possible ground states. We also discuss the presence of a critical distance below which two antiferromagnetically ordered vortices form a strongly coupled ``vortex molecule'' that behaves as a single object and has only one eigenmode.

submitted to Phys. Rev. B ()

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Cited by in corpus (5)

• Spectroscopy of the fractional vortex eigenfrequency in a long Josephson 0-kappa junction
• Controllable plasma energy bands in a 1D crystal of fractional Josephson vortices
• Non-ideal artificial phase discontinuity in long Josephson 0-kappa-junctions
• Semifluxon molecule under control
• Thermal escape of fractional vortices in long Josephson junctions