The fate of hyperuniform vortex patterns at the surface of type II superconductors

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

Bariloche

Workshop; Yielding phenomena in disordered systems; 2019

Instituto Balseiro

A many particle system must posses long-range interactions in order to be hyperuniform at thermal equilibrium. Hydrodynamic arguments and numerical simulations show, nevertheless, that a three-dimensional elastic-line array with short-ranged repulsive interactions, such as the one induced and directed by a magnetic field along the z-direction in a superconductor, form at equilibrium a class II hyperuniform two-dimensional point pattern in any constant-z cross section, with point density fluctuations vanishing isotropically as a power law with exponent one at small wavevectors q. This prediction includes both the solid and liquid vortex phases in the absence of disorder, and also the liquid phase in presence of weak uncorrelated quenched disorder. We show that the three-dimensional Bragg-glass phase is marginally hyperuniform, while the Bose-glass and the liquid-phase with columnar disorder are expected to be non-hyperuniform at equilibrium, with the exception of the Mott-Glass phase. Motivated by these theoretical predictions and recent simulations we ex perimentally study large wavelength vortex density fluctuations of magnetically decorated vortex structures in pristine, electron irradiated and heavy-ion irradiated BSSCO superconducting samples in the mixed state.For most of our samples we find nearly hyperuniform two-dimensional point patterns at the superconductor surface with an effective exponent approximately one. We interpret these results in terms of a large-scale memory of the high-temperature line-liquid phase due to glassy dynamics during the field-cooling protocol. We also discuss the crossovers expected from the dispersivity of the elastic constants at intermediate length-scales, and how finite-size effects in the z-direction should kill the hyperuniformity in the x-y plane for lengths1/q above the superconductor thickness. We argue these predictions may be observable and propose further experiments to independently test them.