Spontaneous vortex state and $\varphi$-junction in a superconducting bijunction with a localized spin
Abstract
A Josephson bijunction made of three superconductors connected by a quantum dot is considered in the regime where the dot carries a magnetic moment. In the range of parameters where such a dot, if inserted in a two-terminal Josephson junction, creates a -shift of the phase, the bijunction forming a triangular unit is frustrated. This frustration is studied both within a phenomenological and a microscopic model. Frustration stabilizes a phase vortex centered on the dot, with two degenerate states carrying opposite vorticities, independently of the direction of the magnetic moment. Embedding the bijunction in a superconducting loop allows to create a tunable ""-junction whose equilibrium phase can take any value. For large enough inductance, it generates noninteger spontaneous flux. Multi-loop configurations are also studied.
Keywords
Cite
@article{arxiv.1405.6889,
title = {Spontaneous vortex state and $\varphi$-junction in a superconducting bijunction with a localized spin},
author = {Denis Feinberg and Carlos Balseiro},
journal= {arXiv preprint arXiv:1405.6889},
year = {2015}
}