Spin waves in doped graphene: a time-dependent spin-density-functional approach to collective excitations in paramagnetic two-dimensional Dirac fermion gases

TL;DR

This paper investigates spin-wave excitations in doped paramagnetic graphene using time-dependent spin-density-functional theory, revealing how doping and spin polarization influence their dispersion and stiffness, with implications for experimental detection.

Contribution

It introduces a theoretical approach to analyze collective spin excitations in doped graphene considering dynamical exchange-correlation effects.

Findings

Spin-wave dispersions depend on doping levels.

Spin stiffness varies with spin polarization.

Potential for experimental observation of spin waves.

Abstract

In spin-polarized itinerant electron systems, collective spin-wave modes arise from dynamical exchange and correlation (xc) effects. We here consider spin waves in doped paramagnetic graphene with adjustable Zeeman-type band splitting. The spin waves are described using time-dependent spin-density-functional response theory, treating dynamical xc effects within the Slater and Singwi-Tosi-Land-Sjolander approximations. We obtain spin-wave dispersions and spin stiffnesses as a function of doping and spin polarization, and discuss prospects for their experimental observation.