to negative Landau damping. The total heat current is from contributions of all those modes. In low frequency region ($\omega<0.1$eV), the heat flux is dominated by the normal Landau damping modes. In high frequency region ($\omega> 0.1$eV), the negative Landau damping modes can be the dominant modes for heat transfer. Due to the unsymmetric nature with an $x$-direction drift current, heat can be transferred from low temperature layer to high temperature layer through the negative Landau damping modes.

![Heat current density as a function of $T_2$ (temperature of the top layer) with drift velocity $v_1=9.0 \times 10^5 \ \mathrm{m/s}$ (red solid line). Dotted line is the reference line for zero current density. The green circle indicates the point for “off temperature”. The chemical potential of graphene $\mu$ is set as 0.1eV. Temperature of bottom layer of graphene $T_1$ is set as 300K. Vacuum gap distance $d$ is set as 10nm. []{data-label="figure3"}](figure3){width="0.85\columnwidth"}

With the help of drift effects, we have demonstrated that the RHT in double-layer graphene can be tuned by the drift velocity, even shutting off or changing sign. To gain a detailed picture of the drift effects, we calculate the heat current density as a function of ${T_2}$ with 