High-temperature surface state in Kondo insulator U<sub>3</sub>Bi<sub>4</sub>Ni<sub>3</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40117363.
- Also identified by DOI 10.1126/sciadv.adq9952 and PMC identifier 11927635.
- Licence recorded as CC BY-NC.
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Abstract
The resurgence of interest in Kondo insulators has been driven by two major mysteries: the presence of metallic surface states and the observation of quantum oscillations. To further explore these mysteries, it is crucial to investigate another similar system beyond the two existing ones, SmB<sub>6</sub> and YbB<sub>12</sub>. Here, we address this by reporting on a Kondo insulator, U<sub>3</sub>Bi<sub>4</sub>Ni<sub>3</sub>. Our transport measurements reveal that a surface state emerges below 250 kelvin and dominates transport properties below 150 kelvin, which is well above the temperature scale of SmB<sub>6</sub> and YbB<sub>12</sub>. At low temperatures, the surface conductivity is about one order of magnitude higher than the bulk. The robustness of the surface state indicates that it is inherently protected. The similarities and differences between U<sub>3</sub>Bi<sub>4</sub>Ni<sub>3</sub> and the other two Kondo insulators will provide valuable insights into the nature of metallic surface states in Kondo insulators and their interplay with strong electron correlations.