Thin Film Nickelate Superconductors: From a Complete Phase Diagram to Pairing Mechanism

Description

Designing and discovering novel quantum materials and architectures pose an exciting frontier in condensed-matter research. In particular, synthesis of new superconductors, especially those with unusual symmetries of superconducting order parameters and/or exotic pairing mechanisms, opens new doors to future applications in quantum devices. Ever since their discovery, high-temperature superconductivity in cuprates has motivated the search for materials with analogous electronic or atomic structure. The recent discovery of superconductivity in a similar system, infinite-layer nickelate, has spurred a surge of research interest. The project proposed herein aims to expand the family of the nickelate superconductors with infinite-layer structure, which offers the materials playground for investigating a wide spectrum of electronic energy landscape and the unconventional pairing mechanism.   The project builds on the following extraordinary advances in the recent years: (1) the atomic-scale synthesis of the epitaxial complex oxide thin films and heterostructures, which host emergent quantum phenomena; (2) the ever-better understanding of high-temperature superconductivity, especially in the cuprate systems; (3) the kinetic-based soft-chemistry approaches that led to the discovery of superconducting nickelates. Specifically, the project will develop synthetic pathways to new members of the nickelate superconductor family, with the potential of having higher transition temperature and Fermi surface ordering instability. By transport and other means, a comprehensive phase diagram enriched with intertwined electronic orders will be established, in which exciting physics will be studied. The proposed work will investigate the intimate interplay between cation composition, superconducting properties and other exotic phases. This project provides an avenue for addressing some of the key materials and physics issues nowadays in the research on the nickelate superconductors.