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arXiv · 2607.29151

Successive Electronic Topological Transitions in the Antiferromagnet UPd$_2$Al$_3$

Adrien Gourgout·Gaël Bastien·Dai Aoki·Gabriel Seyfarth·Ilya Sheikin·Andrey Varlamov·Gertrud Zwicknagl·Jacques Flouquet·Georg Knebel·Alexandre Pourret
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Abstract

We report successive anomalies at low temperature in the magnetic field dependence of the thermoelectric signal in the heavy fermion compound UPd$_{2}$Al$_{3}$ inside the antiferromagnetic state up to the metamagnetic transition at $H_\text{M} =18$~T. Based on renormalisation perturbation theory and the partitioning of the $f$ orbitals into localized and delocalized parts, our analysis attributes these anomalies to complex topological changes of the Fermi surface driven by Zeeman effect. The observation of a sudden change of sign both in the thermoelectric power and in the Hall coefficient at $H_\text{M}$ in addition to the appearance of large quantum oscillations in the thermoelectric power above $H_\text{M}$ indicate a strong Fermi surface reconstruction at the metamagnetic transition due to the unfolding of the electronic bands.

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Adrien Gourgout, Gaël Bastien, Dai Aoki, Gabriel Seyfarth, Ilya Sheikin, Andrey Varlamov, Gertrud Zwicknagl, Jacques Flouquet, Georg Knebel, Alexandre Pourret. 2026-07-31. Successive Electronic Topological Transitions in the Antiferromagnet UPd$_2$Al$_3$. https://arxiv.org/abs/2607.29151

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