Fragility of the Kondo insulating gap against disorder: relevance to recent puzzles in topological Kondo insulators

Abstract

Kondo insulators are strongly correlated system in which a clean insulating gap emerges only at very low temperature due to many-body effects involving localized $f$-electrons. However, certain Kondo insulators, like SmB${}_6$ and Ce${}_3$Bi${}_4$Pt${}_3$, display metallic behaviors at extremely low temperatures, that have defied current understanding. Recent advances in topological effects in materials has raised the attention on the protected surface states in these "topological Kondo insulators" as a potential resolution to some of the puzzling behaviors. Here we resolve these puzzles via a different route, by showing that the emergent Kondo insulating scale is extremely vulnerable against moderate degree of disorder, such that the gap is filled with a small number of states. Therefore, the real samples are probably never truly insulating and this in turn compromises the essential building block of topological considerations. Our results suggest strongly that systems like the Slater insulators would be a more promising direction to extend the realm of topology to strongly correlated systems.

arXiv commentAccepted in Physical Review Research

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Cited by in corpus (8)

• Resistivity saturation in Kondo insulators
• Critical role of magnetic moments in heavy-fermion materials: revisiting mysteries of SmB${}_6$
• Hall anomaly, Quantum Oscillations and Possible Lifshitz Transitions in Kondo Insulator YbB${}_{12}$: Evidence for Unconventional Charge Transport
• Ground state of Ce${}_3$Bi${}_4$Pd${}_3$ unraveled by hydrostatic pressure
• An STM perspective on hexaborides: Surface states of the Kondo insulator SmB${}_6$
• Slow crystalline electric field fluctuations in the Kondo lattice SmB${}_6$
• Phase stability in SmB${}_6$
• Surface excitations relaxation in the Kondo insulator Sm${}_{1-x}$Gd${}_x$B${}_6$