Reduction Optimization for Superconducting Lanthanum Nickelates

Infinite-layer nickelates are promising candidates for studying unconventional superconductivity because of their electronic and structural similarities with the cuprates [1-2]. Despite their similarities, theoretical calculations of the infinite-layer nickelate band structure have revealed properties that differ from the cuprates, including the presence of electron pockets in the Fermi surface, which creates a “self-doping” effect to make the ground state of the parent compound metallic with no long-range magnetic order observed to date [3-4]. The study of nickelates is limited because the poor thermodynamic stability of the system constrains synthesis to nanometer-scale thin films, with challenges in maintaining high crystallinity [4-7]. Our ongoing efforts to optimize materials growth and subsequent topotactic reduction have substantially improved the synthesis of infinite-layer lanthanum nickelate (LaNiO₂) and reduced the transport scattering effects of disorder. Investigation of topotactic reduction from the parent perovskite to infinite-layer phase allow us to construct a phase diagram in the space of reduction time and temperature that determine optimal parameters for transport measurements.

References

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