Dataset: Superconductivity in the parent infinite-layer nickelate NdNiO₂

Authors: C. T. Parzyck ¹, Y. Wu ¹, L. Bhatt ², M. Kang ^1,3,4, Z. Arthur ⁵, T. M. Pedersen⁵, R. Sutarto ⁵, S. Fan⁶, J. Pelliciari⁶, V. Bisogni ⁶, G. Herranz ⁷, A. B. Georgescu ⁸, D. G. Hawthorn ⁹, L. F. Kourkoutis ^2,4, D. A. Muller ^2,4, D. G. Schlom ^3,4,10, K. M. Shen ^1,4,7

Author affiliations:
¹:Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
²:School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
³:Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
⁴:Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
⁵:Canadian Light Source, Inc., 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
⁶:National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
⁷:Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB Bellaterra 08193, Spain
⁸:Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
⁹:Department of Physics and Astronomy, University of Waterloo, Waterloo ON N2L 3G1, Canada
¹⁰:Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, Germany

We report evidence for superconductivity with onset temperatures up to 11 K in thin films of the infinite-layer nickelate parent compound NdNiO₂. A combination of oxide molecular beam epitaxy and atomic hydrogen reduction yields samples with high crystallinity and low residual resistivities, a substantial fraction of which exhibit superconducting transitions. We survey a large series of samples with a variety of techniques, including electrical transport, scanning transmission electron microscopy, x-ray absorption spectroscopy, and resonant inelastic x-ray scattering, to investigate the possible origins of superconductivity. We propose that superconductivity could be intrinsic to the undoped infinite-layer nickelates but suppressed by disorder due to a possibly sign-changing order parameter, a finding which would necessitate a reconsideration of the nickelate phase diagram. Another possible hypothesis is that the parent materials can be hole doped from randomly dispersed apical oxygen atoms, which would suggest an alternative pathway for achieving superconductivity.