Hyperuniformity in vortex matter in type-II superconductors

Many biological, material and mathematical systems share the special property of being hyperuniform, namely of presenting vanishing infinite-wavelength density fluctuations. This means that the density of the constituent objects is homogeneous in the large scale, as in a perfect crystal, although they can be isotropic and disordered like a liquid. Hyperuniform structures present a structure factor that algebraically decays to zero when decreasing the reciprocal-space wavenumber q due to the suppression of particle density fluctuations at large direct-space length-scales. This "hidden order" present in disordered systems can be affected by the type of disorder of the host medium where the objects are nucleated. Vortex matter nucleated at the surface of superconducting samples with weak point-like disorder are ordered and disordered hyperuniform systems.[1,2] In this work we study experimentally and theoretically how planar correlated disorder in the medium affects this property. We show that correlated strong disorder generated by planes of defects traversing the whole sample thickness suppress the hyperuniformity of the structure. This particular type of disorder produces a structure factor that decays at small wavenumbers but saturates in the limit q->0 due to persisting vortex density fluctuations at large lengthscales. We also show that this suppression is concomitant to anisotropic vortex density fluctuations.