SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 44: Focus Session: Superconducting Nickelates I

TT 44.3: Hauptvortrag

Donnerstag, 30. März 2023, 10:30–11:00, HSZ 03

Superconducting instabilities in strongly-correlated infinite-layer nickelates — •Andreas Kreisel — Niels Bohr Institute, University of Copenhagen, Denmark

Unconventional superconductivity is often referred to as originating from a pairing mechanism different from electron-phonon interactions and connected to an anisotropic superconducting order parameter with sign change of the Cooper pair wavefunction. In this talk, I will start from a discussion of the mechanism of spin-fluctuation mediated pairing that can lead to d-wave states as evidenced in the cuprate superconductors, but also the sign-changing s_± state that seems to be realized in Fe-based superconductors. The discovery of superconductivity in infinite-layer nickelates has immediately posed the question about the pairing mechanism and the pairing symmetry in this system and sparked proposals of analogs towards well studied families of materials in the class of unconventional superconductors. To connect to this open question, the leading superconducting instability is computed from magnetic fluctuations relevant for infinite-layer nickelates incorporating the strongly correlated multi-orbital nature of the low-energy electronic degrees of freedom. Observing the interplay between the Ni d_x²−y² and d_z² orbitals as well as the self-doping band, a transition from d-wave pairing symmetry to nodal s_± superconductivity is uncovered. This is driven by strong fluctuations in the d_z²-dominated orbital states. As probe of the detailed superconducting gap structure, we discuss the properties of the resulting superconducting condensate in light of tunneling and penetration depth experiments.