Near-field radiative heat transfer of nanoparticles mediated by moving metasurfaces

The bidirectional symmetry of electromagnetic wave propagation in optomechanical systems can be effectively disrupted, leading to the achievement of novel devices for unconventional photon transport. This article investigates the near-field radiative heat transfer (NFRHT) between nanoparticles based on moving metasurfaces. The modeling is based on isotropic silicon carbide (SiC) particles and a graphene metasurface and the NFRHT is analyzed using the Green's function and conductivity approximation. This study reveals that when the velocity of the metasurface is sufficiently high, the radiative heat flux in the near field becomes highly nonreciprocal. By selecting appropriate chemical potentials and particle arrangement positions, the thermal conductivity coefficient can be enhanced or suppressed by up to five orders of magnitude. The required threshold velocity for the thermal diode we constructed is also significantly reduced under specific chemical potentials. These findings provide theoretical support for scenarios involving high-speed relative motion in the near field.

Figure 1

Moving metasurface controlling nonreciprocal transmission of near-field radiation of nanoparticles.

Figure 2

(a) Response of the $x$-direction wave vector magnitude and propagation length on the graphene surface to velocity under different chemical potentials, where the rad and blue lines represent the wave vector magnitude and propagation length, respectively. (b) Spectral thermal flux coefficient under different velocities and chemical potentials, where ${\omega }_r=1.756\times {10}^{14} \mathrm{rad}/\mathrm{s}$ represents the resonant frequency of SiC particles. (c) The response of the spectral thermal flux coefficient at ${\omega }_r$ to velocity under different chemical potentials. Here, $d=1\mu \mathrm{m}$ and $\beta =v/c$.

Figure 3

When the chemical potential is (a) $0.1\mathrm{eV}$ and (b) $0.5\mathrm{eV}$, the spatial dispersion of the surface wave vector varies at different velocities. When the chemical potential is $0.5\mathrm{eV}$, and $\beta$ is (c) 0, (d) 0.05, and (e) 0.1, the contour of the wave vector for the first part $\mathrm{Re}\left[{\mathbb{G}}^{sc}(1,1)\right]$ of the Green's function reflection matrix.

Figure 4

Energy density distribution contour maps in the cross-sectional plane at $h=60\text{nm}$ and in the longitudinal plane at $y=0\text{nm}$, considering (a) the absence of the metasurface and the presence of the metasurface with chemical potentials of (b) $0.1\mathrm{eV}$ for the velocities take on the values of 0, 0.02, and 0.1 and (c) $0.5\mathrm{eV}$ for the velocities take on the values of 0, 0.04, 0.06, and 0.1.

Figure 5

(a) Illustration of particles' deflection. (b) Distribution contour maps of dispersion curves and real part of the first part of the reflection Green's function in the $S^{\prime }$ system for $\mu =0.5\mathrm{eV}, \beta =0.1$, and $\theta ={60}^{\circ }$. Variation curves of the spectral thermal flux coefficient in the $S^{\prime }$ system with respect to deflection angle and velocity for (c) $\mu =0.1\mathrm{eV}$ or (d) $\mu =0.5\mathrm{eV}$. Panels (e) and (f) represent contour maps of the spectral thermal flux coefficient as a function of surface velocity and particle deflection angle with chemical potentials of $0.1\mathrm{eV}$ and $0.5\mathrm{eV}$. The calculations were performed using ${\log }_{10}(H_{{\omega }_r}/H_{{\omega }_{r}0})$, where $H_{{\omega }_{r}0}$ represents the spectral thermal flux coefficient at angle $\theta$ when $\beta$ is equal to 0.

Figure 6

Distribution contour maps of the spectral thermal flux coefficient in the $S^{\prime }$ system for particles at (a) $\theta =0^{\circ }$ and (b) $\theta ={180}^{\circ }$ as a function of chemical potential and surface velocity. (c) Distribution contour map of the spectral thermal rectification coefficient $\eta =(H_{{\omega }_r}^{0^{\circ }}-H_{{\omega }_r}^{{180}^{\circ }})/max\left[(H_{{\omega }_r}^{0^{\circ }},H_{{\omega }_r}^{{180}^{\circ }})\right]$.

Figure 7

Variation of the spectral thermal flux coefficient with the particles' spacing and velocity at chemical potentials of (a) $0.1\mathrm{eV}$ and (b) $0.5\mathrm{eV}$. Variation of the spectral thermal flux coefficient with particle-to-surface distance and velocity at chemical potentials of (c) $0.1\mathrm{eV}$ and (d) $0.5\mathrm{eV}$.