Intrinsic Low-Temperature Magnetism in SmB6

Abstract

By means of new muon spin relaxation experiments, we disentangle extrinsic and intrinsic sources of low-temperature bulk magnetism in the candidate topological Kondo insulator (TKI) SmB6. Results on Al-flux grown SmB6 single crystals are compared to those on a large floating-zone grown ^{154}Sm^{11}B6 single crystal in which a 14 meV bulk spin exciton has been detected by inelastic neutron scattering. Below ~ 10 K we detect the gradual development of quasi-static magnetism due to rare-earth impurities and Sm vacancies. Our measurements also reveal two additional forms of intrinsic magnetism: 1) underlying low-energy (~ 100 neV) weak magnetic moment (~ 10^{-2} mu_B) fluctuations similar to those detected in the related candidate TKI YbB12 that persist down to millikelvin temperatures, and 2) magnetic fluctuations consistent with a 2.6 meV bulk magnetic excitation at zero magnetic field that appears to hinder surface conductivity above ~ 4.5 K. We discuss potential origins of the magnetism.

arXiv comment6 pages, 4 figures

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• Critical role of magnetic moments in heavy-fermion materials: revisiting mysteries of SmB${}_6$
• Shubnikov-de Haas Oscillations and Nontrivial Topological State in a New Weyl Semimetal Candidate SmAlSi
• Electronic and magnetic properties of the topological semimetal SmMg${}_2$Bi${}_2$
• Magnetoquantum Oscillations in the Specific Heat of a Topological Kondo Insulator
• Phase stability in SmB${}_6$
• Surface excitations relaxation in the Kondo insulator Sm${}_{1-x}$Gd${}_x$B${}_6$