Freezing out of a low-energy bulk spin exciton in SmB6

Kolawole Akintola, Anand Pal, Sarah R. Dunsiger, Alex C.Y. Fang, Matt Potma, Shanta R. Saha, Xiangfeng Wang, Johnpierre Paglione, Jeff E. Sonier

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The Kondo insulator SmB6 is purported to develop into a robust topological insulator at low temperatures. Yet there are several puzzling and unexplained physical properties of the insulating bulk. It has been proposed that bulk spin excitons may be the source of these anomalies and may also adversely affect the topologically protected metallic surface states. Here, we report muon spin rotation measurements of SmB6 that show thermally activated behavior for the temperature dependence of the transverse-field relaxation rate below 20 K and a decreasing contact hyperfine field contribution to the positive muon Knight shift below 5-6 K. Our data are consistent with the freezing out of a bulk low-energy (~1 meV) spin exciton concurrent with the appearance of metallic surface conductivity. Furthermore, our results support the idea that spin excitons play some role in the anomalous low-temperature bulk properties of SmB6.

Original languageEnglish
Article number36
Journalnpj Quantum Materials
Issue number1
Publication statusPublished - 01-12-2018

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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