Role of the interface for superconductivity in infinite-layer nickelate films

The stabilization of superconducting infinite-layer nickelates [1] provides a long-awaited experimental platform to explore a close analogue of the high-T_c cuprates. As the family of superconducting nickelate thin films grows [2-4], superconductivity remains unreported in bulk samples, raising questions about the origin of superconductivity in these samples. In particular, the polar interface between the SrTiO₃ substrate and RNiO₂ (R = rare earth) films has been proposed to host a two-dimensional electron gas (2DEG) with very high carrier density [5]. Leveraging high-resolution electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM), we reveal the atomic-scale lattice structure and charge distribution at the nickelate-substrate interface. Informed by systematically varied theoretical models, we provide a more complete understanding of the role played by this interface for superconductivity. 

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3. Osada, et al. Advanced Materials, 2104083 (2021).

4. Pan, et al. Nature Materials, in press (2021).

5. Geisler & Pentcheva, Phys. Rev. B 102, 020502 (2020).