Collective Interference of Phonon Spin and Dipole Moment Rotation Induced Circular Dichroism

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Classical phonon spin theory assumes simple elastic field rotation.
• Complex lattices with multiple atoms per unit cell challenge this classical view.
• Microscopic vibrational particles necessitate a re-evaluation of phonon spin.

Purpose of the Study:

• To investigate the nature of phonon spin in real materials with complex lattices.
• To demonstrate how collective interference of atoms influences phonon spin.
• To link collective interference phonon spin to observable phenomena like dipole moment rotation.

Main Methods:

• Derivation of infrared circular dichroism (ICD) considering phonon-photon interactions in complex lattices.
• Modeling collective interference phonon spin as dipole moment rotation (DMR).
• Comparison of DMR with local atom rotation effects on ICD spectra.

Main Results:

• Phonon spin in complex lattices is a collective interference phenomenon, not a simple sum of atomic rotations.
• Collective interference manifests as dipole moment rotation (DMR) of charge-polarized unit cells.
• Distinct ICD spectra differentiate collective interference DMR from local atom rotation.

Conclusions:

• Collective interference plays a crucial role in determining phonon spin in real materials.
• Phonon spin in complex lattices offers deeper insights into material properties.
• Proposed detectable ICD measurements in α quartz highlight experimental relevance.