Infrared magneto-spectroscopy of two-dimensional and three-dimensional massless fermions: A comparison.

Here, we report on a magneto-optical study of two distinct systems hosting massless fermions--two-dimensional graphene and three-dimensional HgCdTe tuned to the zero band gap condition at the point of the semiconductor-to-semimetal topological transition. Both materials exhibit, in the quantum regime, a fairly rich magneto-optical response, which is composed from a series of intraand interband inter-Landau level resonances with for massless fermions typical √B dependence. The impact of the system's dimensionality and of the strength of the spin-orbit interaction on the optical response is also discussed. [ABSTRACT FROM AUTHOR]