Evidence of weakened 4<i>f</i>-5<i>d</i> Kondo hybridization and diminished valence fluctuations concurrent with the formation of the metallic surface state in SmB<sub>6</sub>
· Invited
Abstract
There is much interest in SmB6 as a potential topological insulator, owing to the robustness of its bulk insulating state originating from the Kondo effect. We have carried out a muon spin rotation (μSR) study of the μ+-Knight shift in SmB6. Our measurements probe bulk rather than surface properties. At low temperatures where Kondo hybridization is complete and at magnetic fields far below what is necessary to close the insulating gap, we observe a magnetic dipolar shift that is indicative of a partially Kondo-compensated Sm moment sublattice. Concomitantly, we detect a contact hyperfine field at the muon site that seems to arise from a direct overlap with the wavefunction of delocalized magnetic Sm-4f electrons. This contact hyperfine field and hence degree of 4f-electron delocalization is strongly reduced below 6 K, where metallic surface states dominate electrical transport. Our results support a ground state in which the insulating bulk is somewhat fragile and on the verge of supporting magnetic order.
*This work is supported by the Natural Sciences and Engineering Research Council of Canada, the Canadian Institute for Advanced Research, Air Force Office of Scientific Research through Grant No. FA9550-14-1-0332, and the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant No. GBMF4419.
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Presenters
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Jeff Sonier
- Physics, Simon Fraser University
- Department of Physics, Simon Fraser University