Resistivity saturation in Kondo insulators

Abstract

Resistivities of heavy-fermion insulators typically saturate below a characteristic temperature $T^{\ast }$. For some, metallic surface states, potentially from a non-trivial bulk topology, are a likely source of residual conduction. Here, we establish an alternative mechanism: At low temperature, in addition to the charge gap, the scattering rate turns into a relevant energy scale, invalidating the semiclassical Boltzmann picture. Finite lifetimes of intrinsic carriers limit conduction, impose the existence of a crossover $T^{\ast }$, and control - now on par with the gap - the quantum regime emerging below it. We showcase the mechanism with realistic many-body simulations and elucidate how the saturation regime of the Kondo insulator Ce${}_3$Bi${}_4$Pt${}_3$, for which residual conduction is a bulk property, evolves under external pressure and varying disorder. Using a phenomenological formula we derived for the quantum regime, we also unriddle the ill-understood bulk conductivity of SmB${}_6$ - demonstrating that our mechanism is widely applicable to correlated narrow-gap semiconductors.

8 pages, 6 figures

References in corpus (4)

• How bad metals turn good: spectroscopic signatures of resilient quasiparticles
• Tuning bulk and surface conduction in topological Kondo insulator SmB6
• Optical properties of correlated materials -- Generalized Peierls approach and its application to VO2
• Thermopower of correlated semiconductors : application to FeAs2 and FeSb2

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• Extraordinary Bulk Insulating Behavior in the Strongly Correlated Materials FeSi and FeSb${}_2$
• Localized f-electron magnetism in the semimetal Ce3Bi4Au3
• Ground state of Ce${}_3$Bi${}_4$Pd${}_3$ unraveled by hydrostatic pressure
• LinReTraCe: The Linear Response Transport Centre
• Pressure-induced concomitant topological and metal-insulator quantum phase transitions in Ce${}_3$Pd${}_3$Bi${}_4$
• Hall response of locally correlated two-dimensional electrons at low density
• Emergent dynamical Kondo coherence and competing magnetic order in a correlated kagome flat-band metal CsCr6Sb6
• Anisotropic Surface State Band Splitting and Low Energy Flat Bands in 3d Correlated Topological Kondo Insulator Candidate FeSb${}_2$
• Universal transport at Lifshitz metal-insulator transitions in two dimensions
• Electronic correlations and topology in Kondo insulator PuB${}_6$
• Prototypical many-body signatures in transport properties of semiconductors