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TT: Fachverband Tiefe Temperaturen

TT 23: Correlated Electrons – Poster I

TT 23.33: Poster

Monday, March 9, 2026, 18:00–20:00, P1

Critical dynamics at isostructural instabilities — •Nick Sander — Karlsruhe Institute of Technology

At an elastic structural instability at least one of the elastic moduli vanishes. An acoustic phonon only softens at such an instability if it is accompanied with a change of crystal symmetry. At isostructural transitions with vanishing bulk modulus, however, no softening occurs and all microscopic phonon modes remain non-critical [1]. Nevertheless, we demonstrate that there exist four macroscopic critical elastic modes that will determine the critical dynamics at such an instability. These modes represent conformal symmetry transformations and the displacement vector satisfy a corresponding Killing equation, whose exact form depends on the crystal symmetry. We discuss implications for instabilities in correlated materials like the Mott metal-insulator transition, and realizations with mechanical metamaterials.
[1] R. A. Cowley, Phys. Rev. B 13, 4877 (1976)

Keywords: Elasticity; Conformal symmetry; Mott transition; Phase transitions; Critical dynamics