  Near-field radiative heat transfer (NFRHT) is strongly related with many
applications such as near-field imaging, thermos-photovoltaics and thermal
circuit devices. The active control of NFRHT is of great interest since it
provides a degree of tunability by external means. In this work, a magnetically
tunable multi-band NFRHT is revealed in a system of two suspended graphene
sheets at room temperature. It is found that the single-band spectra for B=0
split into multi-band spectra under an external magnetic field. Dual-band
spectra can be realized for a modest magnetic field (e.g., B=4 T). One band is
determined by intra-band transitions in the classical regime, which undergoes a
blue shift as the chemical potential increases. Meanwhile, the other band is
contributed by inter-Landau-level transitions in the quantum regime, which is
robust against the change of chemical potentials. For a strong magnetic field
(e.g., B=15 T), there is an additional band with the resonant peak appearing at
near-zero frequency (microwave regime), stemming from the magneto-plasmon zero
modes. The great enhancement of NFRHT at such low frequency has not been found
in any previous systems yet. This work may pave a way for multi-band thermal
information transfer based on atomically thin graphene sheets.
