Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Fe-based Superconductors - Other Materials and Theory

TT 15.9: Talk

Monday, April 1, 2019, 17:00–17:15, H23

Finite electronic correlations and two-dome superconductivity across a clean nematic quantum phase transition — •Pascal Reiss¹, David Graf², Amir A Haghighirad^1,3, William Knafo⁴, Loïc Drigo^4,5, Matt Bristow¹, Andrew J Schofield⁶, and Amalia I Coldea¹ — ¹Clarendon Laboratory, University of Oxford, UK — ²National High Magnetic Field Laboratory, Florida State University, Tallahassee, USA — ³Institut fur Festkörperphysik, Karlsruhe Institute of Technology, Germany — ⁴Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Toulouse, France — ⁵Géosciences Environnement Toulouse (CNRS), Toulouse, France — ⁶School of Physics and Astronomy, University of Birmingham, UK

In the proximity of a nematic quantum critical point, electronic nematic fluctuations have been identified as a candidate for enhancing superconductivity in various unconventional superconductors. However, the coexistence of long-range magnetic order has hindered detailed studies of nematic criticality. To address this challenge, we combine chemical pressure in FeSe_1−xS_x to suppress long-range magnetic order, and physical pressure to study the uncovered, clean nematic quantum phase transition. Using magneto-transport and quantum oscillations measurements, we trace the strength of electronic correlations and their role played in promoting superconductivity. We demonstrate that electronic correlations remain finite, the Fermi surface suffers a Lifshitz transition, and superconductivity is weakened across the nematic quantum phase transition. We interpret these results in light of recent theoretical and experimental advances, and sample quality.