Metallic surface states in a correlated d-electron topological Kondo insulator candidate FeSb2

Abstract

The resistance of a conventional insulator diverges as temperature approaches zero. The peculiar low temperature resistivity saturation in the 4f Kondo insulator (KI) SmB6 has spurred proposals of a correlation-driven topological Kondo insulator (TKI) with exotic ground states. However, the scarcity of model TKI material families leaves difficulties in disentangling key ingredients from irrelevant details. Here we use angle-resolved photoemission spectroscopy (ARPES) to study FeSb2, a correlated d-electron KI candidate that also exhibits a low temperature resistivity saturation. On the (010) surface, we find a rich assemblage of metallic states with two-dimensional dispersion. Measurements of the bulk band structure reveal band renormalization, a large temperature-dependent band shift, and flat spectral features along certain high symmetry directions, providing spectroscopic evidence for strong correlations. Our observations suggest that exotic insulating states resembling those in SmB6 and YbB12 may also exist in systems with d instead of f electrons.

References in corpus (28)

• Topological Kondo Insulators
• Symmetry-based Indicators of Band Topology in the 230 Space Groups
• Surface electronic structure of the topological Kondo insulator candidate correlated electron system SmB6
• Low-temperature surface conduction in the Kondo insulator SmB${}_6$
• Quantum oscillations in Kondo Insulator SmB${}_6$
• 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
• Direct observation of the spin texture in strongly correlated SmB6 as evidence of the topological Kondo insulator
• Surface and Bulk Electronic Structure of the Strongly Correlated System SmB${}_6$ and Implications for a Topological Kondo Insulator
• Cubic Topological Kondo Insulators
• Anisotropy and large magnetoresistance in narrow gap semiconductor FeSb2
• Tuning bulk and surface conduction in topological Kondo insulator SmB6
• Quantum Oscillations of Electrical Resistivity in an Insulator
• Kondo Insulator description of spin state transition in FeSb2
• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Thermopower of correlated semiconductors : application to FeAs2 and FeSb2
• Samarium hexaboride: A trivial surface conductor
• Thermoelectricity in correlated narrow-gap semiconductors
• Huge Thermoelectric Power Factor: FeSb2 versus FeAs2 and RuSb2
• Surface Kondo Effect and Non-Trivial Metallic State of the Kondo Insulator YbB12
• 4$f$ crystal field ground state of the strongly correlated topological insulator SmB${}_6$
• Unchanged thermopower enhancement at the semiconductor-metal transition in correlated FeSb${}_{2-x}$Te${}_x$
• Temperature dependent effective mass renormalization in a Coulomb Fermi liquid
• Strongly enhanced temperature dependence of the chemical potential in FeSe
• Anisotropic Correlated Electronic Structure of Colossal Thermopower Marcasite FeSb${}_2$
• Enhanced electron correlations in FeSb${}_2$
• Study for material analogs of FeSb${}_2$: material design for thermoelectric materials

Cited by in corpus (9)

• Prediction of unconventional magnetism in doped FeSb2
• Probing FeSi, a d-electron topological Kondo insulator candidate, with magnetic field, pressure, and microwaves
• Extraordinary Bulk Insulating Behavior in the Strongly Correlated Materials FeSi and FeSb${}_2$
• Correlated Topological Mixed-Valence Insulators in Moiré Hetero-Bilayers
• Topological zero modes and correlation pumping in an engineered Kondo lattice
• Spin-orbit coupling effects over thermoelectric transport properties in quantum dots
• Surface Conductivity in Antiferromagnetic Semiconductor CrSb${}_2$
• Anisotropic Surface State Band Splitting and Low Energy Flat Bands in 3d Correlated Topological Kondo Insulator Candidate FeSb${}_2$
• Prototypical many-body signatures in transport properties of semiconductors