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TT: Fachverband Tiefe Temperaturen

TT 37: Ruthenates

TT 37.4: Talk

Wednesday, March 29, 2023, 15:45–16:00, HSZ 201

Giant lattice softening at a Lifshitz transition in the normal state of Sr₂RuO₄ — •Hilary M. L. Noad¹, Kousuke Ishida¹, You-Sheng Li¹, Veronika Stangier², Naoki Kikugawa³, Dmitry A. Sokolov¹, Bongjae Kim⁴, Igor I. Mazin⁵, Markus Garst², Jörg Schmalian², Andrew P. Mackenzie^1,6, and Clifford W. Hicks^1,7 — ¹Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ²Karlsruhe Institute of Technology, Karlsruhe, Germany — ³National Institute for Materials Science, Tsukuba, Japan — ⁴Kunsan National University, Gunsan, Korea — ⁵George Mason University, Fairfax, USA — ⁶University of St Andrews, St Andrews, UK — ⁷University of Birmingham, Birmingham, UK

The interplay between lattice and electronic degrees of freedom is a central theme in condensed matter physics. In Sr₂RuO₄, the quasi-two-dimensional Fermi surface can be tuned through a Lifshitz transition—a change in its topology—with uniaxial pressure along the ⟨100⟩ direction. We investigated the influence of this electronic transition on the lattice by using a piezo-based uniaxial pressure cell to measure the stress-strain relation of Sr₂RuO₄ across the Lifshitz transition. We find a large and strongly temperature-dependent softening of the [100] Young’s modulus at the Lifshitz transition. From thermodynamic arguments and comparison to a tight-binding model, we establish that the softening is indeed driven by conduction electrons.