Modulating Near-Field Radiative Heat Transfer in Multi-Body Systems

Active control of near-field radiative heat transfer (NFRHT) between multi-body systems has attracted great attention. Investigation of innovative methods for controlling radiative heat flow, analogous to electric current manipulation, has attracted significant attention. This interest arises due to the growing importance of such techniques in nanodevices designed for thermal management and heat-to-electricity conversion. The ability to control the magnitude and direction of heat flow at the micro/nanoscale has enabled various devices such as thermal diodes, transistors, switches, logic gates/circuits, and memories. Several methods have been proposed and explored in the literature to optimize our leverage over thermal radiative transfer, including employing metal-insulator transition materials, applying a magnetic field to magneto-optical materials, and tuning the chemical potential of graphene. Despite the remarkable progress, the above methods are usually limited in their operating temperature or the achievable heat flow contrast. To overcome these constraints, researchers have started to pursue a temperature-independent and noncontact approach to modulate NFRHT with minimum structural change dynamically. In this regard, recent theoretical works on nanoscale radiative heat transfer involving multiple anisotropic bodies have suggested the potential of these materials to regulate radiative heat flows. Recent theoretical studies have demonstrated that anisotropic materials, whose properties depend on the orientation of their optical axis regarding thermal radiation, hold promise in regulating radiative heat flows. Adjusting their relative orientation makes it possible to easily enhance or suppress the overall heat flux. While controlling NFRHT between isotropic materials can be only achieved by fabricating nanostructured metamaterials like gratings or nanoholes, multi-body systems consisting of anisotropic materials will be a promising alternative for controlling NFRHT without changing the structural properties of the system.<br/><br/>This work presents a comprehensive theoretical study of near-field heat transfer in a three-body planar system with a uniaxial intermediate layer and examines the regulation effects of the relative orientation of the middle layer on the total radiative heat flux. In the proposed system, both source and the observer layers are made of polar material, which supports surface phonon polariton (SPhPs), while the middle layer is a uniaxial thin layer capable of supporting surface modes. By employing the launder formalism for NFRHT on a system consisting of three distinct planar plates, we show how the anisotropic properties of the intermediate layer can substantially mediate the overall radiative heat transfer within the system. This modulation approach is achieved by varying the orientation of the optical axis of the middle layer. Moreover, the effect of different materials, gap distances, and the thickness of the intermediate layer on the heat transfer regulation is investigated. Using this configuration, the equilibrium temperature of the intermediate layer can also be regulated by twisting and adjusting the relative angle of the intermediate layer. The proposed method enables the control of nanoscale radiative heat flux, offering great potential for thermal management applications via contactless heat flux control.