Hear the Sound of Weyl Fermions

Abstract

Quasiparticles and collective modes are two fundamental aspects that characterize a quantum matter in addition to its ground state features. For example, the low energy physics for Fermi liquid phase in He-III was featured not only by Fermionic quasiparticles near the chemical potential but also by fruitful collective modes in the long-wave limit, including several different sound waves that can propagate through it under different circumstances. On the other hand, it is very difficult for sound waves to be carried by the electron liquid in the ordinary metals, due to the fact that long-range Coulomb interaction among electrons will generate plasmon gap for ordinary electron density fluctuation and thus prohibits the propagation of sound waves through it. In the present paper, we propose a unique type of acoustic collective modes in Weyl semimetals under the magnetic field called chiral zero sound. The chiral zero sound can be stabilized under so-called "chiral limit", where the intra-valley scattering time is much shorter than the inter-valley one, and only propagates along an external magnetic field for Weyl semimetals with multiple-pairs of Weyl points. The sound velocity of the chiral zero sound is proportional to the field strength in the weak field limit, whereas it oscillates dramatically in the strong field limit, generating an entirely new mechanism for quantum oscillations through the dynamics of neutral bosonic excitation, which may manifest itself in the thermal conductivity measurements under magnetic field.

9+16 pages, 2+0 figures, a new appendix added, accepted in PRX

References in corpus (13)

• The Chiral Magnetic Effect
• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase
• Topological response in Weyl semimetals and the chiral anomaly
• Classification of stable three-dimensional Dirac semimetals with nontrivial topology
• Berry Curvature, Triangle Anomalies, and the Chiral Magnetic Effect in Fermi Liquids
• Chiral Anomaly and Diffusive Magnetotransport in Weyl Metals
• Thermoelectric properties of Weyl and Dirac semimetals
• Plasmon mode as a detection of the chiral anomaly in Weyl semimetals
• Consistent Chiral Kinetic Theory in Weyl Materials: Chiral Magnetic Plasmons
• Detecting Chiral Magnetic Effect by Lattice Dynamics
• Density response in Weyl metals
• Collective Modes of Chiral Kinetic Theory in Magnetic Field

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• Phonon-limited Transport and Fermi Arc Lifetime in Weyl Semimetals
• Moiré optical phonons dancing with heavy electrons in magic-angle twisted bilayer graphene
• Gravitational anomaly in the ferrimagnetic topological Weyl semimetal NdAlSi
• Severe violation of the Wiedemann-Franz law in quantum oscillations of NbP
• Unpaired topological triply degenerate point for spin-tensor-momentum-coupled ultracold atoms
• Detection of relativistic fermions in Weyl semimetal TaAs by magnetostriction measurements
• Inverse-current quantum electro-oscillations in a charge-density wave insulator
• Bipolarized Weyl semimetals and quantum crystal valley Hall effect in two-dimensional altermagnetic materials
• Non-Abelian interference of topological edge states
• Collective effects in an incompressible electronic liquid