Landau-level radiation in current-injected monolayer graphene

Monolayer graphene has a gapless and linear dispersion. Thanks to this unique dispersion, monolayer graphene has unequally Landau levels (LLs) and an extra LL at the charge neutral point. In this paper, we investigated the spectrum of infrared radiation from current-injected graphene under high magnetic fields. The experimental results indicate that infrared radiation is attributed to the inter-LL radiative transition with a narrower linewidth than expected from magnetotransport measurements.