Hidden one-dimensional, strongly nested, and almost half-filled Fermi surface in Ba2CuO3+y superconductors

All previous cuprate superconductors display a set of common features: (i) vicinity to a Cu 3d9 configuration; (ii) separated CuO2 planes; and (iii) superconductivity for doping 8 - 0.1-0.3. Recently, Li et al. [Proc. Natl. Acad. Sci. USA 116, 12156 (2019)] challenged this picture by discovering highly overdoped superconducting Ba2CuO3+y. Using density-functional theory plus dynamical mean-field theory, we reveal a bilayer structure of Ba2CuO3.2 of alternating quasi-two-dimensional (2D) and quasi-one-dimensional (1D) character. Correlations tune an interlayer self-doping leading to an almost half-filled, strongly nested, quasi-1D db2-c2 band, which is prone to strong antiferromagnetic fluctuations, possibly at the origin of superconductivity in Ba2CuO3+y.

Automated summary

In this study, a bilayer structure of Ba2CuO3+y was revealed using density-functional theory and dynamical mean-field theory. It was found that interlayer self-doping leads to a quasi-one-dimensional band with strong nesting and antiferromagnetic fluctuations, possibly responsible for the superconductivity in Ba2CuO3+y.