Hyperuniform patterns nucleated at low temperatures: Insight from vortex matter imaged in unprecedentedly large fields-of-view

Hyperuniform patterns present enhanced physical properties that make them the new generation of cutting-edge technological devices. Synthesizing devices with tens of thousands of components arranged in a hyperuniform fashion has thus become a breakthrough to achieve in order to implement these technologies. Here we provide evidence that extended two-dimensional hyperuniform patterns spanning tens of thousands of components can be nucleated using as a template the low-temperature vortex structure obtained in pristine Bi2Sr2CaCu2O8 samples after following a field-cooling protocol.

💡 Research Summary

The authors investigate whether the vortex lattice formed in a high‑temperature superconductor can serve as a large‑scale template for hyperuniform patterns—structures that suppress density fluctuations at long wavelengths and thus possess superior physical properties. Using pristine, nearly optimally doped Bi₂Sr₂CaCu₂O₈ (BSCCO) single crystals with thicknesses greater than 20 µm and only weak point‑like disorder, they performed a field‑cooling (FC) protocol: the sample was cooled from the normal state under a modest magnetic field of 30 Oe to 4.2 K, freezing the vortex configuration. Magnetic decoration, in which ferromagnetic particles settle on the vortex cores, provided panoramic images of the vortex positions. By stitching together many such images they obtained unprecedented fields of view containing up to ~33 000 vortices, far exceeding previous studies limited to a few thousand vortices.

The vortex positions were digitized and analyzed via Delaunay triangulation, revealing a quasi‑long‑range ordered Bragg‑glass state with occasional grain boundaries and topological defects (5‑fold and 7‑fold coordinated vortices). The two‑dimensional structure factor S(q) was computed by Fourier transforming the density field of vortex tips. Regardless of the field‑of‑view size, S(q) displayed an algebraic decay as q→0: S(q)≈B(q/q₀)^α with α≈1.46 for the largest dataset and α≈1.40 for the smallest. Since 1 < α < 2, the vortex arrangement belongs to the class‑II (type‑I II) hyperuniform category, characterized by a slower-than‑random decay of density fluctuations (σ_N²∝R^β with β=2−α between 0 and 1).

To test whether the observed exponent could be explained by elastic‑theory corrections, the authors also fitted the data to S(q)=C(q/q₀)