Near-field electromagnetic heat transfer through nonreciprocal hyperbolic graphene plasmons

In the present work, we theoretically demonstrate that near-field radiative heat transfer (NFRHT) can be modulated and enhanced by a new energy transmission mode of evanescent wave, i.e. the nonreciprocal hyperbolic surface plasmon polaritons (NHSPPs). It is well known that by patterning a single layer of graphene sheet into ribbons, the closed circular dispersion of graphene plasmons is opened to become hyperbolic one. When a drift current is applied to a graphene ribbon, this hyperbolic model would evolve into the extremely asymmetric shape, which has never been noted in the noncontact heat exchanges at nanoscale before. Combining the analysis of dispersion distribution, we find that as the drift velocity increases, the hyperbolic mode exhibits more significant asymmetric characteristics. It is also found that under a larger gap size, the enhanced effect of NHSPPs on NFRHT can be weakened. In addition, the coupling effect of grating and drift current is investigated simultaneously. By changing the chemical potential and graphene filling factor, the positions and intensities of the modes can be modulated, and hence the NFRHT can be tuned accordingly. Finally, we have found that thanks to the nonreciprocal hyperbolic topology of the system, at a large twisted angle, the system with a large drift current velocity is more preferable to modulate the NFRHT compared with the zero-current case. In summary, the findings may open a promising pathway for highly efficient thermal management, energy harvesting, and subwavelength thermal imaging.