Quantum Nonlinear Acoustic Hall Effect and Inverse Acoustic Faraday Effect in Dirac Insulators.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Topological insulators exhibit unique electronic properties governed by band topology.
• Dirac insulators possess a band structure with linear dispersion, similar to graphene.
• Acoustic waves can interact with electronic systems, potentially inducing novel phenomena.

Purpose of the Study:

• To investigate the realization of quantum nonlinear Hall and inverse Faraday effects using acoustic waves in Dirac insulators.
• To explore the role of intrinsic valley-contrasting band topology in these phenomena.
• To understand the tunability of topological currents and static magnetization via acoustic wave properties.

Main Methods:

• Theoretical modeling of acoustic wave interaction with time-reversal invariant, inversion-broken Dirac insulators.
• Analysis of acoustoelectric conductivity and magnetoacoustic susceptibility.
• Investigation of interband transition suppression at low acoustic frequencies.

Main Results:

• Quantum nonlinear Hall and inverse Faraday effects are shown to arise from band topology.
• Acoustoelectric conductivity and magnetoacoustic susceptibility are proportional to the quantized valley Chern number.
• Topological currents and static magnetization are tunable by acoustic wave polarization and propagation.

Conclusions:

• A quantized nonlinear topological acoustoelectric response is unveiled in gapped Dirac materials.
• The findings suggest potential for room-temperature acoustoelectric devices utilizing materials like hexagonal boron nitride and transition-metal dichalcogenides.