Plasmons in bias-induced topological phase transition in black phosphorus

TL;DR

This paper studies how bias-induced topological phase transitions in bilayer black phosphorus affect plasmon modes, revealing new acoustic plasmons and changes in dielectric loss due to Fermi surface topology shifts.

Contribution

It develops an effective two-band Hamiltonian to accurately model the electronic transition and its impact on plasmon behavior in biased bilayer black phosphorus.

Findings

Appearance of an additional linearly dispersing acoustic plasmon mode

Modification of dielectric loss due to Fermi surface topology change

Fermi surface transitions from disc to ring or dual pockets

Abstract

We investigate the plasmons in bilayer black phosphorus (BP) with bias-driven formation of Dirac cones, by developing an effective two-band Hamiltonian that captures this electronic transition with great accuracy. We show that the appearance of the Dirac cones lead to additional linearly dispersing acoustic plasmon mode, in conjunction to the conventional plasmon. In addition, the change in the Fermi surface topology from a disc to ring or dual pockets also modifies the dielectric loss.