The intermediate-valence compound SmB6 is a well-known Kondo insulator, in which hybridization of itinerant 5d electrons with localized 4f electrons leads to a transition from metallic to insulating behavior at low temperatures. Recent studies suggest that SmB6 is a topological insulator, with topological metallic surface states emerging from a fully insulating hybridized bulk band structure. Here we locally probe the bulk magnetic properties of pure and 0.5 % Fe-doped SmB6 by muon spin rotation/relaxation methods. Below 6 K the Fe impurity induces simultaneous changes in the bulk local magnetism and the electrical conductivity. In the low-temperature insulating bulk state we observe a temperature-independent dynamic relaxation rate indicative of low-lying magnetic excitations driven primarily by quantum fluctuations.
@article{arxiv.1702.02198,
title = {Quantum spin fluctuations in the bulk insulating state of pure and Fe-doped SmB6},
author = {K. Akintola and A. Pal and M. Potma and S. R. Saha and X. F. Wang and J. Paglione and J. E. Sonier},
journal= {arXiv preprint arXiv:1702.02198},
year = {2017}
}