Sensitivity of electronic structure to crystal distortions in infinite-layered LaNiO2

Abstract

Recent observations of unconventional superconductivity (SC) in thin films of LaNiO2 (critical temperature 𝑇c≃ 10 K) and in bulk single crystals of La3⁢Ni2⁢O7 under pressure 𝑇c≃80K have cemented a long sought-after class of SC nickelates. In La1−𝑥⁢Sr⁢𝑥⁢NiO2, SC appears only in films for reasons not understood. We perform a combination of experiments to probe the crystal structure and magnetic order in bulk LaNiO2 together with ab initio calculations of the electronic structure. We find that the infinite layers are naturally buckled out-of-plane. The electronic bands are largely unaffected by the buckling, but uniaxial compression along the 𝑐 axis may lead to a Lifshitz transition.