Quantum Oscillations and Charge-Neutral Fermions in Topological Kondo Insulator YbB12

The electronic state of every solid is classified into insulator or metal. A Fermi surface plays a key role in most physical properties in metals. Quantum oscillations are a periodic response of physical quantities with respect to external magnetic fields. This book presents a comprehensive review of recent observations of quantum oscillations in the Kondo insulators, SmB6 and YbB12, and discusses how the observations are demonstrated by a newly proposed mechanism where emergent charge-neutral fermions exhibit quantum oscillations instead of bare electrons. It also focuses on topological properties of Kondo insulators, and demonstrates that YbB12 hosts a surface metallic conduction due to its non-trivial band structure. Further, it presents the experiments of specific heat and thermal conductivity in YbB12 down to ultra-low temperature to discuss the possible low-energy excitations from a Fermi surface of neutral fermions.

Format: Paperback / softback
Length: 86 pages
Publication date: 06 November 2022
Publisher: Springer Verlag, Singapore

The electronic state of every solid can be broadly categorized into two distinct categories based on its electrical responses: insulators and metals. In the realm of modern solid state physics, a textbook explains that the shape of a Fermi surface holds a crucial role in determining the majority of physical properties in metals. One established experimental technique to detect a Fermi surface is the measurement of quantum oscillations, which are periodic responses of physical quantities to external magnetic fields. Interestingly, insulators, which do not host a Fermi surface, are believed to lack the manifestation of quantum oscillations.

This book offers a comprehensive exploration of recent observations of quantum oscillations in the Kondo insulators, SmB6, and YbB12. These observations are substantiated by a novel mechanism wherein emergent charge-neutral fermions exhibit quantum oscillations rather than bare electrons. Furthermore, the book delves into the topological properties of Kondo insulators, showcasing that YbB12 hosts a surface metallic conduction due to its non-trivial band structure. Additionally, the book presents experimental measurements of specific heat and thermal conductivity in YbB12 down to ultra-low temperatures to discuss the potential existence of low-energy excitations originating from a Fermi surface of neutral fermions. The observed gapless and itinerant fermionic excitations, which constitute a substantial contribution from charge-neutral fermions, violate the Wiedemann-Franz law. These discoveries highlight a remarkable phase of quantum state: electrically insulating yet thermally metallic, realized in the bulk of topological Kondo insulators.

Weight: 174g
Dimension: 235 x 155 (mm)
ISBN-13: 9789811656798
Edition number: 1st ed. 2021