  In this Rapid Communication, 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 surface plasmons
polaritons (NSPPs). In addition to the well-known coupled surface plasmon
polaritons (SPPs), applying a drift current on a graphene sheet leads to an
extremely asymmetric photonic transmission model, which has never been noted in
the noncontact heat exchanges at nanoscale before. The coupling of plasmons in
the infrared bands dominates the NFRHT, associated with low loss (high loss and
ultrahigh confinement) traveling along (against) the current. The dependence of
NSPPs on the drift-current velocity as well as the vacuum gap is analyzed. It
is found that the coupling of NSPPs at smaller and larger gap sizes exhibits
different nonreciprocities. Finally, we also demonstrate that the prominent
influence of the drift current on the radiative heat flux is found at a low
chemical potential. These findings will open a new way to spectrally control
NFRHT, which holds great potential for improving the performance of energy
systems like near-field thermophotovoltaics and thermal modulator.
