Visualizing the atomic-scale origin of metallic behavior in Kondo insulators

Abstract

A Kondo lattice is often electrically insulating at low temperatures. However, several recent experiments have detected signatures of bulk metallicity within this Kondo insulating phase. Here we visualize the real-space charge landscape within a Kondo lattice with atomic resolution using a scanning tunneling microscope. We discover nanometer-scale puddles of metallic conduction electrons centered around uranium-site substitutions in the heavy-fermion compound URu${}_2$Si${}_2$, and around samarium-site defects in the topological Kondo insulator SmB${}_6$. These defects disturb the Kondo screening cloud, leaving behind a fingerprint of the metallic parent state. Our results suggest that the mysterious 3D quantum oscillations measured in SmB${}_6$ could arise from these Kondo-lattice defects, although we cannot rule out other explanations. Our imaging technique could enable the development of atomic-scale charge sensors using heavy-fermion probes.

References in corpus (39)

• Complexity in Strongly Correlated Electronic Systems
• An Intrinsic Bond-Centered Electronic Glass with Unidirectional Domains in Underdoped Cuprates
• Magnetic impurities on the surface of a topological insulator
• Robust Surface Hall Effect and Nonlocal Transport in SmB6: Indication for an Ideal Topological Insulator
• Observation of in-gap surface states in the Kondo insulator SmB6 by photoemission
• Unconventional Fermi surface in an insulating state
• Imaging the Fano Lattice to 'Hidden Order' Transition in URu2Si2
• Quantum Oscillation from In-gap States and non-Hermitian Landau Level Problem
• Fermi surface instability at the hidden-order transition of URu2Si2
• Electron Cotunneling into a Kondo Lattice
• Quantum oscillations without a Fermi surface and the anomalous de Haas-van Alphen effect
• A Tunable Two-impurity Kondo system in an atomic point contact
• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Scanning Quantum Dot Microscopy
• Interacting Antiferromagnetic Droplets in Quantum Critical CeCoIn_5
• Differential Conductance and Quantum Interference in Kondo Systems
• Skyrme insulators: insulators at the brink of superconductivity
• Imaging emergent heavy Dirac fermions of a topological Kondo insulator
• Anomalous 3D bulk AC conduction within the Kondo gap of SmB${}_6$ single crystals
• Quantum oscillations in flux-grown SmB6 with embedded aluminum
• Robustness of the Insulating Bulk in the Topological Kondo Insulator SmB${}_6$
• How Kondo Holes Create Intense Nanoscale Heavy-Fermion Hybridization Disorder
• Magnetic and defect probes of the SmB${}_6$ surface state
• Breakdown of the Kondo insulating state in SmB6 by introducing Sm vacancies
• Majorana Fermi Sea in Insulating SmB6: A proposal and a Theory of Quantum Oscillations in Kondo Insulators
• Orbital-selective Kondo-lattice and enigmatic f-electrons emerging from inside the antiferromagnetic phase of a heavy fermion
• Defects in Heavy-Fermion Materials: Unveiling Strong Correlations in Real Space
• Consistency between ARPES and STM measurements on SmB${}_6$
• Properties of the donor impurity band in mixed valence insulators
• Observation of a well-defined hybridization gap and in-gap states on the SmB6 (001) surface
• Visualizing the atomic-scale origin of metallic behavior in Kondo insulators
• Observation of backscattering induced by magnetism in a topological edge state
• Quantum Engineered Kondo Lattices
• Quantum Oscillations of Electrons and of Composite Fermions in Two Dimensions: Beyond the Luttinger Expansion
• Magnetic impurities in Kondo insulators: An application to samarium hexaboride
• Quantum spin fluctuations in the bulk insulating state of pure and Fe-doped SmB6
• Bulk transport paths through defects in floating zone and Al flux grown SmB${}_6$
• Spin-selective tunneling from nanowires of the candidate topological Kondo insulator SmB6
• Metallic islands in the Kondo insulator SmB${}_6$

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