Hyperuniform vortex patterns at the surface of type-II superconductors

RUMI, GONZALO; ARAGÓN SÁNCHEZ, JAZMÍN; ELÍAS, FEDERICO; CORTÉS MALDONADO, RAÚL; PUIG, JOAQUÍN; CEJAS BOLECEK, NÉSTOR RENÉ; NIEVA, GLADYS; KONCZYKOWSKI, MARCIN; FASANO, YANINA; KOLTON, ALEJANDRO B.

Physical Review Research

American Physical Society

Año: 2019 vol. 1 p. 33057 - 33057

A many-particle system must possess long-range interactions in order to be hyperuniform at thermalequilibrium. Hydrodynamic arguments and numerical simulations show, nevertheless, that a three-dimensionalelastic-line array with short-ranged repulsive interactions, such as vortex matter in a type-II superconductor,forms at equilibrium a class-II hyperuniform two-dimensional point pattern for any constant-z cross section. Inthis case, density fluctuations vanish isotropically as ∼qα at small wave vectors q, with α = 1. This predictionincludes the solid and liquid vortex phases in the ideal clean case and the liquid in presence of weak uncorrelateddisorder. We also show that the three-dimensional Bragg glass phase is marginally hyperuniform, while theBose glass and the liquid phase with correlated disorder are expected to be nonhyperuniform at equilibrium.Furthermore, we compare these predictions with experimental results on the large-wavelength vortex densityfluctuations of magnetically decorated vortex structures nucleated in pristine, electron-irradiated, and heavy-ionirradiatedsuperconducting Bi2Sr2CaCu2O8+δ samples in the mixed state. For most cases, we find hyperuniformtwo-dimensional point patterns at the superconductor surface with an effective exponent αeff ≈ 1. We interpretthese results in terms of a large-scale memory of the high-temperature line-liquid phase retained in the glassydynamics when field cooling the vortex structures into the solid phase. We also discuss the crossovers expectedfrom the dispersivity of the elastic constants at intermediate length-scales, and the lack of hyperuniformity in thex -y plane for lengths q−1 larger than the sample thickness due to finite-size effects in the z direction. We arguethese predictions may be observable and propose further imaging experiments to test them independently.