Majoranas in mixed-valence insulators

Abstract

A physical model for a mixed-valence impurity in a metal must satisfy the Friedel screening theorem for both valences. Such a model is shown, following earlier work which showed low energy singularities in it, to be supersymmetric, leading to a free Majorana and a phase-shifted Majorana excitation. The theory extended approximately to a lattice of mixed-valence ions at appropriate filling gives, without fine-tuning the parameters, a protected gapless Majorana fermion band across the chemical potential, besides the mixed-valence particle and hole bands separated by gaps. In this situation the system is electrically neutral in linear response but has de Haas-van Alphen oscillations. This is used to explain the recently observed magneto-oscillations in mixed-valence insulators as well as their accompanying low energy thermodynamic and relaxation rate anomalies. Some predictions to test the validity of the theoretical results are provided, the most striking of which is that there should be extensive ground state entropy in such compounds.

References in corpus (14)

• Unpaired Majorana fermions in quantum wires
• Topological Kondo Insulators
• Quantum oscillations in Kondo Insulator SmB${}_6$
• Unconventional Fermi surface in an insulating state
• Odd Frequency Pairing in the Kondo Lattice
• Quantum Oscillations of Electrical Resistivity in an Insulator
• Quantum oscillations without a Fermi surface and the anomalous de Haas-van Alphen effect
• Correlation between bulk thermodynamic measurements and the low temperature resistance plateau in SmB6
• Skyrme insulators: insulators at the brink of superconductivity
• Quantum oscillations in insulators with neutral Fermi surfaces
• Fermi surfaces in Kondo insulators
• Topological surface states interacting with bulk excitations in the Kondo insulator SmB${}_6$ revealed via planar tunneling spectroscopy
• Majorana Fermi Sea in Insulating SmB6: A proposal and a Theory of Quantum Oscillations in Kondo Insulators
• Low-temperature magnetic fluctuations in the Kondo insulator SmB6

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• Solvable Periodic Anderson Model with Infinite-Range Hatsugai-Kohmoto Interaction: Ground-states and beyond
• $f$-electron hybridised metallic Fermi surface in magnetic field-induced metallic YbB${}_{12}$
• Quantum Oscillations in the Magnetisation and Density of States of Insulators
• Hall anomaly, Quantum Oscillations and Possible Lifshitz Transitions in Kondo Insulator YbB${}_{12}$: Evidence for Unconventional Charge Transport
• Charge neutral fermions and magnetic field driven instability in insulating YbIr${}_3$Si${}_7$
• Fluctuation-dominated quantum oscillations in excitonic insulators
• Correlated Topological Mixed-Valence Insulators in Moiré Hetero-Bilayers
• Magnetoquantum Oscillations in the Specific Heat of a Topological Kondo Insulator
• Quantum Oscillations in an Impurity-Band Anderson Insulator
• Notes on Quantum oscillation for Hatsugai-Kohmoto model
• A Mean-Field Study of Quantum Oscillations in Two-Dimensional Kondo Insulators
• Mixed-valence state in the dilute-impurity regime of La-substituted SmB${}_6$
• Quantum oscillations in the heat capacity of Kondo insulator YbB12
• Enhancement of charge-neutral fermionic excitation near spin-flop transition\\ in magnetic Kondo material YbIr${}_3$Si${}_7$
• Anomalous 4$f$ fine structure in TmSe${}_{1-x}$Te${}_x$ across the metal-insulator transition
• Theoretical investigation of quantum oscillations of specific heat in Kondo insulators