Interaction driven subgap spin exciton in the Kondo insulator SmB6

W T Fuhrman; J Leiner; P Nikolić; G E Granroth; M B Stone; M D Lumsden; L DeBeer-Schmitt; P A Alekseev; J-M Mignot; S M Koohpayeh; P Cottingham; W Adam Phelan; L Schoop; T M McQueen; C Broholm

doi:10.1103/PhysRevLett.114.036401

Interaction driven subgap spin exciton in the Kondo insulator SmB6

Phys Rev Lett. 2015 Jan 23;114(3):036401. doi: 10.1103/PhysRevLett.114.036401. Epub 2015 Jan 21.

Authors

W T Fuhrman¹, J Leiner², P Nikolić³, G E Granroth⁴, M B Stone², M D Lumsden², L DeBeer-Schmitt⁵, P A Alekseev⁶, J-M Mignot⁷, S M Koohpayeh¹, P Cottingham⁸, W Adam Phelan⁸, L Schoop⁹, T M McQueen¹⁰, C Broholm¹¹

Affiliations

¹ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
² Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
³ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, Virginia 22030, USA.
⁴ Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
⁵ Instrument Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
⁶ National Research Centre "Kurchatov Institute," 123182 Moscow, Russia and National Research Nuclear University "MEPhI," 115409 Moscow, Russia.
⁷ Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif sur Yvette, France.
⁸ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
⁹ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
¹⁰ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
¹¹ Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.

PMID: 25659009
DOI: 10.1103/PhysRevLett.114.036401

Abstract

Using inelastic neutron scattering, we map a 14 meV coherent resonant mode in the topological Kondo insulator SmB6 and describe its relation to the low energy insulating band structure. The resonant intensity is confined to the X and R high symmetry points, repeating outside the first Brillouin zone and dispersing less than 2 meV, with a 5d-like magnetic form factor. We present a slave-boson treatment of the Anderson Hamiltonian with a third neighbor dominated hybridized band structure. This approach produces a spin exciton below the charge gap with features that are consistent with the observed neutron scattering. We find that maxima in the wave vector dependence of the inelastic neutron scattering indicate band inversion.