Fig. 1. Concept and implementation for NFRHT. (a) Material-engineered near-field heating and cooling under nonequilibrium drift. (b) Schematic setup for radiative heat transfer. The top layer is a graphene metasurface at temperature T1, which is electrically biased along y direction, and the electron drifting velocity is vd. The bottom layer is AMDHM covered with a graphene metasurface at temperature T2. The AMDHM is realized by embedding SiC nanowires into magnetic host hyperbolic metamaterials. f is volume filling factor of SiC NWs. In the calculation, the parameters are as follows: L=10nm, W=5nm, G=5nm, d=100nm, T1=T2=300K, vd=0.4vF. Here, vF is the Fermi velocity of graphene.

Fig. 2. (a) Dependence of radiative heat flux Q on volume filling factor f. (b) Contour plot of heat flux spectral function q(ω) as a function of volume filling factor f and frequency ω. Three vertical slash lines indicate f=0.2,0.5,0.8. Note that we use arbitrary unit for q(ω).

Fig. 3. Contour plot of kx-integrated energy transmission function B as a function of ω and ky. Spectral function q(ω)(=∫Bdky) at fixed f is plotted on the side. (a) f=0.2. (b) f=0.5. (c) f=0.8. Black dashed lines in contour plots represent dispersion relation of surface plasmon–phonon polaritons obtained at kx=0. Heating and cooling peaks in the curve of q(ω) are marked as ω+ and ω−, respectively. Note that we use arbitrary unit for B and q(ω).

Fig. 4. Contour plot of energy transmission function A as a function of (kx,ky) at fixed f and ω. kx-integrated energy transmission function B(=∫Adkx) is plotted on the side. (a), (b) f=0.2. (c), (d) f=0.5. (e), (f) f=0.8. ω+ and ω− correspond to the heating and cooling peaks in Fig. 3, respectively. Note that we use arbitrary unit for A and B.