Current loops, phase transitions, and the Higgs mechanism in Josephson-coupled multicomponent superconductors

Abstract

The N-component London U(1) superconductor is expressed in terms of integer-valued supercurrents. We show that the inclusion of interband Josephson couplings introduces monopoles in the current fields, which convert the phase transitions of the charge-neutral sector to crossovers. The monopoles only couple to the neutral sector, and leave the phase transition of the charged sector intact. The remnant noncritical fluctuations in the neutral sector influence the one remaining phase transition in the charged sector, and may alter this phase transition from a 3DXY inverted phase transition into a first-order phase transition depending on what the values of the gauge charge and the intercomponent Josephson coupling are. This preemptive effect becomes more pronounced with increasing number of components N, since the number of charge-neutral fluctuating modes that can influence the charged sector increases with N. We also calculate the gauge-field correlator, and by extension the Higgs mass, in terms of current-current correlators. We show that the onset of the Higgs mass of the photon (Meissner effect) is given in terms of a current loop blowout associated with going into the superconducting state as the temperature of the system is lowered.

Source-reported materials — not catalogue approval

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