Correlated structural distortions in the cuprate superconductors*

Nanoscale electronic inhomogeneity is a well-known aspect of perovskite-related quantum materials. Measurements of superconducting (SC) fluctuations above the bulk SC transition temperature in cuprates and other oxide superconductors revealed a universal inhomogeneity-dominated regime indicative of underlying structural inhomogeneity [1]. We studied several cuprate superconductors using neutron and X-ray diffuse scattering and found short-range-correlated structural distortions over wide doping and temperature ranges. Using structure modelling and the 3D-ΔPDF method [2], we reveal the real-space structure associated with these distortions and find atomic shifts perpendicular to the CuO₂ planes, with a characteristic length scale similar to the SC correlation length. Along with a recent phenomenological model of the cuprates [3], these insights pave the way toward a comprehensive understanding of cuprate superconductivity.

[1] D. Pelc et al., Nat. Commun. 9, 4327 (2018); G. Yu et al., Phys. Rev. B. 99, 214502 (2019); D. Pelc et al., Nat. Commun. 10, 2729 (2019)
[2] M. J. Krogstad et al., Nat. Mater. 19, 63 (2019)
[3] D. Pelc et al., Sci. Adv. 5, eaau4538 (2019)