SKM 2021 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 19: Unconventional Superconductors
TT 19.6: Talk
Thursday, September 30, 2021, 12:30–12:45, H6
Quasiparticle Interference of the van-Hove singularity in Sr2RuO4 — •Andreas Kreisel1, Carolina A. Marques2, Luke C. Rhodes2, Xiangru Kong3, Tom Berlijn3, Rosalba Fittipaldi4, Veronica Granata5, Antonio Vecchione4, Peter Wahl2, and Peter J. Hirschfeld6 — 1Institut für Theoretische Physik, Universität Leipzig — 2SUPA, University of St Andrews,UK — 3CNMS, Oak Ridge National Laboratory, USA — 4CNR-SPIN, UOS Salerno, Italy — 5Dipartimento di Fisica, Università di Salerno, Italy — 6Department of Physics, University of Florida, USA
The single-layered ruthenate Sr2RuO4 is one of the most enigmatic unconventional superconductors. While for many years it was thought to be the best candidate for a chiral p-wave superconducting ground state, desirable for topological quantum computations, recent experiments suggest a singlet state, ruling out the original p-wave scenario. The superconductivity as well as the properties of the multi-layered compounds of the ruthenate perovskites are strongly influenced by a van Hove singularity in proximity of the Fermi energy. Tiny structural distortions move the van Hove singularity across the Fermi energy with dramatic consequences for the physical properties. Here, we determine the electronic structure of the van Hove singularity in the surface layer of Sr2RuO4 by quasiparticle interference imaging. We trace its dispersion and demonstrate from a model calculation accounting for the full vacuum overlap of the wave functions that its detection is facilitated through the octahedral rotations in the surface layer.