Shift of the collective mode of polarized graphene on a substrate using spin-sensitive response theory

Abstract

The growing precision of optical and scattering experiments necessitates a better understanding of the influence of damping onto the collective mode of sheet electrons. As spin-polarized systems are of particular interest for spintronic applications, we here report spin-sensitive linear response functions of graphene, which give access to charge-and spin-density related excitations. We further calculate the reflectivity of graphene on an SiO2 surface, a setup used in s-wave scanning near field microscopy. Increasing the partial spin-polarization of the graphene charge carriers leads to a significant broadening and shift of the plasmon mode, due to single-particle interband transitions of the minority spin carriers. We also predict an antiresonance in the longitudinal magnetic response function, similar to that of semiconductor heterostructures.

Dynamic response of partially spin- and valley-polarised two-dimensional electron liquids

“…In Dirac 2DELs with partial spin or valley polarisation, the gapless interband Landau damping prevents long-lived modes 9 , but the ARs, where a sub-species cannot keep up with stimulation, do not require a gap [46]. Other modern unconventional 2DELs like silicene or TMDs are gapped and thus will share many of the dynamical features presented here.…”

“…Graphene electrons have a much richer (q, ω)-spectrum than quantum well 2DELs. Increasing ζ σ at ζ τ = 0 drastically broadens the √ q-plasmon by gapless interband Landau damping; the mAR, where interactions with n ↓spins inhibit an n ↑ -response, is qualitatively changed from an intraband excitation suppression to one in the interband continuum above the charge plasmon [46]. Certainly, in partially valley-polarised graphene and TMDs, fascinating dynamic properties await discovery.…”