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TT: Fachverband Tiefe Temperaturen

TT 25: f-Electron Systems

TT 25.6: Vortrag

Dienstag, 10. März 2026, 10:45–11:00, HSZ/0101

Acoustic signatures of field-induced electronic topological transitions in YbNi₄P₂ — •Jérémy Sourd¹, E.O. Eljaouhari², B.V. Schwarze¹, K. Kliemt³, C. Krellner³, F. Husstedt^1,4, J. Wosnitza^1,4, S. Zherlitsyn¹, and G. Zwicknagl^2,5 — ¹Dresden High Magnetic Field Laboratory (HLDEMFL), HZDR, Germany — ²Institut für Mathematische Physik, TU Braunschweig — ³Physikalisches Institut, Johann Wolfgang Goethe-Universität, Frankfurt am Main — ⁴Institut für Festkörper- und Materialphysik, TU Dresden — ⁵Max Planck Institute for Chemical Physics of Solids, Dresden

The Fermi surface is a central concept to elaborate the physical properties of correlated electron systems. While resulting from the precise chemistry of a given material through its crystal and electronic structures, the Fermi-surface shape and topology can evolve drastically upon varying a control parameter leading to an electronic-topological transition (ETT). In heavy-fermion systems the strong electronic correlations generate renormalized flat bands close to the Fermi level, leading to effective Fermi energies of the order of 10 T. Thus, in these systems the Zeeman energy from moderate magnetic field is enough to induce an ETT, as observed for example in YbNi₄P₂. We used acoustic waves in order to probe the sequence of ETT in YbNi₄P₂, by performing ultrasound experiments at low temperature. By comparing the observed anomalies of the sound velocity for different acoustic modes, we show how ultrasound permits to better explore the reciprocal space structure of the ETTs in YbNi₄P₂.

Keywords: electronic-topological transition; ultrasound; quantum oscillations; heavy fermions