Anisotropic plasmons, Friedel oscillations, and screening in $8\text{\ensuremath{-}}Pmmn$ borophene

Anisotropic plasmons, Friedel oscillations, and screening in $8 − P m m n$ borophene

Krishanu Sadhukhan and Amit Agarwal

Phys. Rev. B 96, 035410 – Published 10 July 2017

Abstract

$8 − P m m n$ borophene is a polymorph of borophene which hosts an anisotropic tilted Dirac cone. Using a low-energy effective Hamiltonian for borophene, we analytically calculate the density-density response function of borophene and study its anisotropic plasmon dispersion and screening properties. We find that the anisotropic plasmon mode in $8 − P m m n$ borophene remains undamped for higher energies along the mirror symmetry direction. The Friedel oscillation in borophene is found to decay as $r^{- 3}$ in the large- $r$ limit, with both the amplitude as well as the periodicity of the Friedel oscillations being anisotropic.