Boosting superconductivity in ultrathin YBa2Cu3O7−δ films via nanofaceted substrates

[This repository contains the raw data for the manuscript "Boosting superconductivity in ultrathin YBa2Cu3O7−δ films via nanofaceted substrates" (arXiv:2502.03986)] In the cuprate high-temperature superconductors doping is fixed during synthesis and the charge carrier density per CuO2 plane cannot be easily tuned by conventional gating, unlike 2D materials. Strain engineering has recently emerged as a powerful tuning knob for manipulating the properties of cuprates, in particular charge and spin orders, and their delicate interplay with superconductivity. In thin films, additional tunability can be introduced by the substrate surface morphology, particularly nanofacets formed by substrate surface reconstruction. Here we show a remarkable enhancement of the superconducting onset temperature Tc,on and the upper critical magneticfield Hc,2 in nanometer-thin YBa2Cu3O7−δ films grown on a substrate with a nanofaceted surface. We theoretically show that the enhancement is driven by electronic nematicity and unidirectional charge density waves, where both elements are captured by an additional effective potential at the interface between the film and the uniquely textured substrate. Our findings show a new paradigm in which substrate engineering can effectively enhance the superconducting properties of cuprates. This approach opens an exciting frontier in the design and optimization of highperformance superconducting materials.