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MA: Fachverband Magnetismus

MA 11: Electron Theory of Magnetism and Correlations (joint session MA/TT)

MA 11.3: Vortrag

Montag, 9. März 2026, 15:30–15:45, POT/0151

Ground State of the Topological Insulator Candidate Eu₂AuGe₃ — •Vinicius Estevo Silva Frehse¹, Aleksandr Sukhanov¹, Artem Korshunov², Eugen Weshcke³, Aly Abdeldaim⁴, Priscila Rosa⁵, and Marein Rahn¹ — ¹Universität Augsburg, Augsburg, Germany — ²Donostia International Physics Center, San Sebastián, Spain — ³Helmholz Zentrum Berlin, Berlin, Germany — ⁴Diamond Light Source, Didcot, UK — ⁵Los Alamos National Laboratory, Los Alamos, USA

Eu₂AuGe₃ is an unusual rare earth germanide in which quasi-trigonal europium sheets are interleaved with Au-Ge honeycomb layers, where high-throughput calculations indicate potential for topological band inversions. Bulk and transport data have revealed a series of (re-)ordering transitions upon cooling, as well as metamagnetic transitions at low temperature. Recently, we identified a broad transition around T_CDW = 130 K as the continuous freezing-out of a buckling mode of the honeycomb layers.

Here, we present preliminary evidence from neutron and resonant elastic X-ray scattering, which hints at helical magnetic order below T_N = 11 K. Unexpectedly for the nominally spin-only divalent europium, the magnetic order also appears to be accompanied by a modulated orbital order parameter. This phase is preceded by a transition at 23 K, where we observe a subtle doubling of the ab-plane, possibly related to the charge density wave formed during T_CDW.

Keywords: Helical magnetism; Rare-earth intermetallics; Resonant scattering; Neutron scattering; Topological materials