Mode shifting due to spin polarization in single layer graphene on a substrate
Sprache des Vortragstitels:
68th Annual Meeting of the Austrian Physical Society
Sprache des Tagungstitel:
Graphene, an almost purely two dimensional system, has opened up new doors into modern
electronics. The growing precision of optical and scattering experiments necessitates a better un-
derstanding of the influence of damping on the collective mode of electrons or holes in such sheets.
Further, the spin of the charge carriers is a promising candidate as an independently manipulable
information carrier in electronic devices, heading towards spintronics.
We report spin-sensitive partial and full linear response functions of graphene, which give access
to charge- and spin-density related excitations. In contrast to two dimensional electron liquids in
heterostructures, graphene?s collective mode can be strongly Landau-damped even at small wave
vectors, due to single-particle interband transitions. Increasing the spin-imbalance of the free charge
carriers in Dirac materials significantly broadens and shifts the plasmon. This enables to switch its
lifetime (its mean free path) by tuning the spin polarization of graphene, thus, in turn, to switch the
efficiency of appliances coupled to this mode.
To bring our results to the test, we calculated the reflectivity of graphene on a SiO2 surface, as
observed in s-wave scanning near field microscopy. The above shift in mode position affects the
dipole interaction function, a key quantity of the measurement. We also predict an antiresonance in
the longitudinal magnetic response, similar to that in semiconductor heterostructures.