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TT: Fachverband Tiefe Temperaturen

TT 41: Unconventional Superconductors

TT 41.6: Vortrag

Mittwoch, 18. März 2020, 16:30–16:45, HSZ 201

Direct observation of a uniaxial stress-driven Lifshitz transition in Sr₂RuO₄ — •Edgar Abarca Morales^1,2, Veronika Sunko^1,2, Igor Markovic^1,2, Mark Barber¹, Dijana Milosavjlevic¹, Federico Mazzola², Dmitry Sokolov¹, Helge Rosner¹, Clifford Hicks¹, Philip King², and Andrew Mackenzie^1,2 — ¹Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany — ²SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, UK

Application of uniaxial pressure has recently been shown to more than double the transition temperature of the unconventional superconductor Sr₂RuO₄, leading to a peak in T_c versus strain whose origin is still under debate. Here we develop a simple and compact method to apply large uniaxial pressures in a way compatible with angle-resolved photoemission. We directly visualise how uniaxial stress drives a Lifshitz transition of the γ-band Fermi surface, pointing to the key role of strain-tuning its associated van Hove singularity to the Fermi level in mediating the peak in T_c. Our measurements provide stringent constraints for theoretical models of the strain-tuned electronic structure evolution of Sr₂RuO₄. Furthermore, our experimental approach opens the door to future studies of strain-tuned phase transitions where large pressure cells or piezoelectric-based devices may be difficult to implement.