Giant lattice softening at a Lifshitz transition in Sr<sub>2</sub>RuO<sub>4</sub>.

Noad, H M L; Ishida, K; Li, Y-S; Gati, E; Stangier, V; Kikugawa, N; Sokolov, D A; Nicklas, M et al. · Science · 2023

biomechanical · Level V

Where this comes from

Abstract

The interplay of electronic and structural degrees of freedom in solids is a topic of intense research. More than 60 years ago, Lifshitz discussed a counterintuitive possibility: lattice softening driven by conduction electrons at topological Fermi surface transitions. The effect that he predicted, however, was small and has not been convincingly observed. Using a piezo-based uniaxial pressure cell to tune the ultraclean metal strontium ruthenate while measuring the stress-strain relationship, we reveal a huge softening of the Young's modulus at a Lifshitz transition of a two-dimensional Fermi surface and show that it is indeed driven entirely by the conduction electrons of the relevant energy band.