A soft chemistry route towards nickelate superconductivity

A curious fact is that, to date, all ambient pressure nickelate superconductors exist in the form of thin films (and more recently as membranes), requiring post-growth soft chemical treatment to activate their superconductivity. This may help explain why nickelate superconductors were discovered much later than cuprates. Moreover, it highlights the crucial role of soft chemical treatment in stabilizing metastable phases of nickelates. In this talk, I would like to elaborate on our efforts to stabilize superconductivity in infinite- and bi-layer nickelate thin films through operando transport feedback during topotactic reduction and oxidation. The methods we present offer a versatile approach that can be applied to a growing family of metastable materials accessible via topochemical processes.