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TT: Fachverband Tiefe Temperaturen

TT 69: Focus Session: Nickelate Superconductivity: Insights into Unconventional Pairing and Correlation Effects II (joint session TT/DS/MA)

TT 69.2: Vortrag

Donnerstag, 12. März 2026, 09:45–10:00, HSZ/0003

ARPES spectra and the role of interstitial-s orbital in infinite-layer nickelates calculated by DFT+DMFT — •Leonard Verhoff¹, Liang Si^1,2, and Karsten Held¹ — ¹Institut für Festkörperphysik, Technische Universität Wien, Wien, Austria — ²School of Physics, Northwest University, Xi’an, China

Infinite-layer nickelates, such as NdNiO₂, 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 NdNiO₂ 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 and band structures for both bulk and slab geometries, 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.

Keywords: Nickelates; Spectroscopy; DFT+DMFT