Local structure of the cuprate superconductors*

The cuprate superconductors have long been known to be electronically inhomogeneous at the nanoscale, although the nature and role of the inhomogeneity remain debated. Recent studies of superconducting fluctuations in cuprates have uncovered a universal inhomogeneity-driven regime in multiple compounds [1], and similar findings for other perovskite-derived superconductors point to universal underlying structural inhomogeneity [2]. Here we present complementary X-ray and neutron diffuse scattering studies of several cuprates, with the real-space local structure determined by the 3D ΔPDF method [3]. The experiments reveal intricate short-range correlated structural distortions, even in HgBa₂CuO_4+δ, which features a simple tetragonal average structure. We discuss the doping dependence of the local structure and correlations with the superconducting T_c.

[1] D. Pelc et al., Nat. Commun. 9, 4327 (2018)
[2] D. Pelc et al., Nat. Commun. 10, 2729 (2019)
[3] M. J. Krogstad et al., Nat. Mater. (2019)