Speaker
Description
Infinite-layer nickelates, such as NdNiO$_2$, are a compelling platform to explore the microscopic origin of unconventional high-temperature superconductivity, from both theoretical and experimental perspectives.
Experimentally, infinite-layer nickelates are reduced from the stable
perovskite phase, leaving an empty apical oxygen site. Density functional theory (DFT) calculations show that the resulting interstitial vacancy hosts localized, $s$-like states about 2 eV above the fermi level, while recent angle-resolved photoemission spectroscopy (ARPES) measurements of superconducting NdNiO$_2$ thin films conjectured Fermi surfaces with major $s$-like orbital character, highlighting a possible role of interstitial-$s$ states in superconductivity.
We present DFT and dynamical mean field theory calculations of
Fermi surfaces, directly comparable to ARPES spectra. Our ARPES simulations explicitly include first-principles photoemission matrix elements, capturing the impact of orbital shapes on the measured intensity. We show how the correlated band structure reproduces low-energy ARPES spectra and identify the features dominated by interstitial-$s$ character.
We acknowledge support through a joint German and Austrian Science
Funds (DFG and FWF) project; FWF project ID I5398.