Intrinsic Low-Temperature Magnetism in SmB6

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 Sm154 B116 si...

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Bibliographic Details
Published in:Physical review letters 2019-11, Vol.123 (19)
Main Authors: Gheidi, S, Akintola, K, Akella, K S, Côté, A M, Dunsiger, S R, Broholm, C, Fuhrman, W T, Saha, S R, Paglione, J, Sonier, J E
Format: Article
Language:English
Subjects:
Crystal growth
Excitons
Inelastic scattering
Low temperature
Magnetic moments
Magnetic variations
Magnetism
Muon spin relaxation
Neutron flux
Neutron scattering
Neutrons
Rare earth elements
Single crystals
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Summary: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 Sm154 B116 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 quasistatic magnetism due to rare-earth impurities and Sm vacancies. Our measurements also reveal two additional forms of intrinsic magnetism: (1) underlying low-energy (∼100  meV) weak magnetic moment (∼10−2  μB) 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.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.123.197203