Intrinsic Low-Temperature Magnetism in SmB_{6}

S Gheidi; K Akintola; K S Akella; A M Côté; S R Dunsiger; C Broholm; W T Fuhrman; S R Saha; J Paglione; J E Sonier

doi:10.1103/PhysRevLett.123.197203

Intrinsic Low-Temperature Magnetism in SmB_{6}

Phys Rev Lett. 2019 Nov 8;123(19):197203. doi: 10.1103/PhysRevLett.123.197203.

Authors

S Gheidi¹, K Akintola¹, K S Akella¹, A M Côté^{1

2}, S R Dunsiger^{1

3}, C Broholm^{4

5

6}, W T Fuhrman⁷, S R Saha⁷, J Paglione^{6

7}, J E Sonier^{1

6}

Affiliations

¹ Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
² Kwantlen Polytechnic University, Richmond, British Columbia V6X 3X7, Canada.
³ Centre for Molecular and Materials Science, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada.
⁴ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
⁵ Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
⁶ Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
⁷ Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.

PMID: 31765191
DOI: 10.1103/PhysRevLett.123.197203

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) SmB_{6}. Results on Al-flux-grown SmB_{6} single crystals are compared to those on a large floating-zone-grown ^{154}Sm ^{11}B_{6} 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} μ_{B}) fluctuations similar to those detected in the related candidate TKI YbB_{12} 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.