Magneto-optical materials have been proposed as promising candidates for an active control of the directionality of nanoscale heat radiation.Here, we NBA Sets discuss the possibility to rectify nanoscale radiative heat fluxes by means of non-reciprocal surface waves and propose a nanoscale heat flux rectifier or diode which can be controlled actively by means of externally applied Floggers fields.We furthermore, reveal the spin coupling mechanism behind the observed heat flux rectification.