Magnetic impurities in Kondo insulators: An application to samarium hexaboride

Abstract

Impurities and defects in Kondo insulators can have an unusual impact on dynamics that blends with effects of intrinsic electron correlations. Such crystal imperfections are difficult to avoid, and their consequences are incompletely understood. Here we study magnetic impurities in Kondo insulators via perturbation theory of the s-d Kondo impurity model adapted to small bandgap insulators. The calculated magnetization and specific heat agree with recent thermodynamic measurements in samarium hexaboride (SmB${}_6$). This qualitative agreement supports the physical picture of multi-channel Kondo screening of local moments by electrons and holes involving both intrinsic and impurity bands. Specific heat is thermally activated in zero field by Kondo screening through sub-gap impurity bands and exhibits a characteristic upturn as the temperature is decreased. In contrast, magnetization obtains a dominant quantum correction from partial screening by virtual particle-hole pairs in intrinsic bands. We point out that magnetic impurities could impact de Haas-van Alphen quantum oscillations in SmB${}_6$, through the effects of Landau quantization in intrinsic bands on the Kondo screening of impurity moments.

References in corpus (22)

• Quantum Oscillation from In-gap States and non-Hermitian Landau Level Problem
• Direct observation of the spin texture in strongly correlated SmB6 as evidence of the topological Kondo insulator
• Hybridization, Inter-Ion Correlation, and Surface States in the Kondo Insulator SmB6
• Quantum Oscillations of Electrical Resistivity in an Insulator
• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Excitons in topological Kondo insulators - theory of thermodynamic and transport anomalies in SmB${}_6$
• Interaction Driven Subgap Spin Exciton in the Kondo Insulator SmB6
• Anomalous 3D bulk AC conduction within the Kondo gap of SmB${}_6$ single crystals
• Surface Theory of a Family of Topological Kondo Insulators
• Fermi surfaces in Kondo insulators
• Robustness of the Insulating Bulk in the Topological Kondo Insulator SmB${}_6$
• Unconventional thermal metallic state of charge-neutral fermions in an insulator
• Quantum oscillations in strongly correlated topological Kondo insulators
• Field-dependent heat transport in the Kondo insulator SmB6 : phonons scattered by magnetic impurities
• In-gap collective mode spectrum of the Topological Kondo Insulator SmB6
• Two-dimensional heavy fermions on the strongly correlated boundaries of Kondo topological insulators
• A highly asymmetric nodal semimetal in bulk SmB6
• A Strongly-Interacting Dirac Liquid on the Surface of a Topological Kondo Insulator
• Suppression of magnetic excitations near the surface of the topological Kondo insulator SmB6
• The Effects of Spin-Excitons on the Surface States of SmB6: A Photoemission Study
• Bulk Rotational Symmetry Breaking in Kondo Insulator SmB6
• Diamagnetic Sm${}^{3+}$ in the topological Kondo insulator SmB${}_6$

Cited by in corpus (8)

• Visualizing the atomic-scale origin of metallic behavior in Kondo insulators
• Intrinsic bulk quantum oscillations in a bulk unconventional insulator SmB${}_6$
• Hall anomaly, Quantum Oscillations and Possible Lifshitz Transitions in Kondo Insulator YbB${}_{12}$: Evidence for Unconventional Charge Transport
• Bulk transport paths through defects in floating zone and Al flux grown SmB${}_6$
• Magnetoquantum Oscillations in the Specific Heat of a Topological Kondo Insulator
• Quantum Oscillations in an Impurity-Band Anderson Insulator
• Local aging effects in PuB${}_4$: Growing inhomogeneity and slow dynamics of local-field fluctuations probed by ${}^{239}$Pu NMR
• Quantum oscillations in the heat capacity of Kondo insulator YbB12