Vortex chains due to nonpairwise interactions and field-induced phase transitions between states with different broken symmetry in superconductors with competing order parameters

Abstract

We study superconductors with two order components and phase separation driven by intercomponent density-density interaction, focusing on the phase where only one condensate has non-zero ground state density and competing order parameter exists only in vortex cores. We demonstrate there, that multi-body intervortex interactions can be strongly non-pairwise, leading to some unusual vortex patterns in external field, such as vortex pairs and vortex chains. We demonstrate that, in external magnetic field, such system undergoes a field-driven phase transition from (broken) U (1) to (broken) U (1)×U (1) symmetries, when subdominant order parameter in the vortex cores acquires global coherence. Observation of these characteristic ordering patterns in surface probes may signal the presence of a subdominant condensate in the vortex core.

Pattern formation in vortex matter with pinning and frustrated intervortex interactions

“…[28,29]. For vortices interacting via non-monotonic repulsive-attractive interactions, vortex pattern formation has been analyzed [10,27,[30][31][32][33][34][35][36], using various models. In particular, vortex clusters, stripes, labyrinths, deformed lattices, and lattices with voids were found [35].…”

Thermal remixing of phase-separated states in two-component bosonic condensates

“…We have been unable to locate the sharp separatrix between these two regions, and whether there are other stable intermediate phases due to the lack of equilibration. Note that this problem is known in other stripe-forming systems where phases are separated by metastable and glassy states [41,42]. The gray area in figure 1 represents upper and lower bounds for the transition.…”

Type-1.5 superconductivity in multicomponent systems

“…Below we discuss the importance of complicated non-pairwise forces between superconducting vortices arising in certain cases in multicomponent systems. 23,43,44 These non-pairwise forces in certain cases have important consequences for vortex clusters formation in the type-1.5 regime.…”

“…Another example of systems that are generally more inclined to posses non-pairwise intervortex forces that promote vortex-stripes are superconducting condensates with phase separation. 43 The Fig. 7 shows the typical non-universal outcome of the energy minimization in this case.…”

“…By gauge invariance, F p may depend only on |ψ 1 |, |ψ 2 | and δ = θ 1 − θ 2 . We consider the regime when F p has a global minimum at some point other than the one with |ψ i | = 0, namely at (|ψ 1 |, |ψ 2 |, δ) = (u 1 , u 2 , 0) where u 1 > 0 and u 2 ≥ 0 (for discussion of phase-separated regimes see 43 ). Then the model has a trivial solution,…”