Boosting superconductivity in ultrathin YBa$_2$Cu$_3$O$_{7-\delta}$ films via nanofaceted substrates

TL;DR

This study demonstrates that nanofaceted substrates can significantly enhance superconductivity in ultrathin YBa2Cu3O7−δ films by inducing electronic nematicity and charge density waves, opening new avenues for superconductor optimization.

Contribution

The paper introduces substrate nanofaceting as a novel method to boost superconducting properties in cuprate thin films, supported by both experimental and theoretical analysis.

Findings

Enhanced superconducting onset temperature and critical magnetic field on nanofaceted substrates.

Electronic nematicity and charge density waves are key to the observed enhancement.

Substrate engineering offers a new paradigm for optimizing high-temperature superconductors.

Abstract

In cuprate high-temperature superconductors the doping level is fixed during synthesis, hence the charge carrier density per CuO$_2$ plane cannot be easily tuned by conventional gating, unlike in 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 $T_{\mathrm{c}}^{\mathrm{on}}$ and the upper critical magnetic field $H_{c,2}$ in nanometer-thin YBa$_2$Cu$_3$O$_{7-\delta}$ 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 high-performance superconducting materials.