Emergent heavy-fermion physics in a new family of topological insulators RAsS (R = Y, La, and Sm)

Iñigo Robredo; Yuan Fang; Lei Chen; Nazar Zaremba; Yurii Prots; Mitja Krnel; Markus König; Thomas Doert; Jeroen van den Brink; Claudia Felser; Qimiao Si; Eteri Svanidze; Maia G. Vergniory

arXiv · 2505.01511

Emergent heavy-fermion physics in a new family of topological insulators RAsS (R = Y, La, and Sm)

Iñigo Robredo·Yuan Fang·Lei Chen·Nazar Zaremba·Yurii Prots·Mitja Krnel·Markus König·Thomas Doert·Jeroen van den Brink·Claudia Felser·Qimiao Si·Eteri Svanidze·Maia G. Vergniory

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Abstract

Realizing topological phases in strongly correlated materials has become a major impetus in condensed matter physics. Although many compounds are now classified as topological insulators, $f$-electron systems (with their strong electron correlations) provide an especially fertile platform for emergent heavy-fermion phenomena driven by the interplay of topology and many-body effects. In this study, we examine the crystalline topology of a new RAsS series (R = Y, La, Sm), revealing a structural variant from previous reports. We demonstrate that YAsS and SmAsS host hourglass fermions protected by glide symmetry. SmAsS notably exhibits a strong effective-mass enhancement, placing it alongside SmB${}_6$ and YbB${}_{12}$ as a material that couples topological surface states with emergent Kondo physics, yet distinguished by its crystalline symmetry constraints and $f$-$p$ orbital hybridization. To capture these features, we construct a minimal model incorporating $f$-electron degrees of freedom, which reproduces the observed topological properties and predicts that the surface states survive in the correlated regime, albeit shifted in energy. Our work thus introduces a new family of correlated topological materials and forecasts the robustness of their surface states under Kondo correlations.

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Iñigo Robredo, Yuan Fang, Lei Chen, Nazar Zaremba, Yurii Prots, Mitja Krnel, Markus König, Thomas Doert, Jeroen van den Brink, Claudia Felser, Qimiao Si, Eteri Svanidze, Maia G. Vergniory. 2025-05-02. Emergent heavy-fermion physics in a new family of topological insulators RAsS (R = Y, La, and Sm). https://arxiv.org/abs/2505.01511

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