Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 81: Correlated Electrons: Other Materials

TT 81.6: Talk

Thursday, March 12, 2026, 16:30–16:45, HSZ/0101

Flat phonons in Eu₂AuGe₃ — •Aleksandr Sukhanov¹, Oleg Utesov², Artem Korshunov³, Vinicius Frehse¹, and Marein Rahn¹ — ¹Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany — ²Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon, Korea, 34126 — ³Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 20018 San Sebastian, Spain

We employed inelastic x-ray scattering (IXS) to study the lattice dynamics in a single crystal of Eu₂AuGe₃ (orthorhombic, space group Fmmm). Within its crystal structure, a structural motif consisting of one Au atom and three Ge atoms plays a special role. Its atomic displacements can be effectively mapped out to the well known electronic cross-stitch model, which is a toy model for the electronic flat bands. We show that the same simple model can be applied to predict a flat phonon mode in Eu₂AuGe₃. In our experimental IXS spectra, we resolve the flat mode and show that it softens on cooling and leads to a charge density wave transition. Our first-principle calculations of the lattice dynamics further support the experimental findings.

Keywords: inelastic x-ray scattering; flat modes; phonons