Raman Scattering as a Selective Probe of Chiral Electronic Excitations in Bilayer Graphene

TL;DR

This study demonstrates that symmetry-resolved electronic Raman scattering can selectively probe chiral electronic excitations in bilayer graphene, revealing unique interference effects that distinguish chiral from non-chiral excitations.

Contribution

The paper introduces a symmetry-resolved ERS technique that isolates chiral excitations in bilayer graphene, highlighting its potential for studying topological and 2D materials.

Findings

Chiral excitations dominate the ERS continuum with Pauli-blocking behavior.

Non-chiral excitations are suppressed due to destructive interference.

Raman scattering can selectively probe chiral degrees of freedom.

Abstract

We report a symmetry resolved electronic Raman scattering (ERS) study of a bilayer graphene device under gate voltage. We show that the ERS continuum is dominated by interband chiral excitations of $A_{2}$ symmetry and displays a characteristic Pauli-blocking behavior similar to the monolayer case. Crucially, we show that non-chiral excitations make a vanishing contribution to the Raman cross-section due to destructive interference effects in the Raman amplitude matrix elements. This is in a marked contrast to optical absorption measurements and opens interesting venues for the use of Raman scattering as a selective probe of chiral degrees of freedom in topological matter and other 2D crystals.