Coupling polaritons in near-field radiative heat transfer between multilayer graphene/vacuum/α-MoO₃/vacuum...

Both materials and structures can significantly affect radiative heat transfer, which is more pronounced in the near-field regime of two-dimensional and hyperbolic materials, and has promising prospects in thermophotovoltaics, radiative cooling, and nanoscale metrology. Hence, it is important to investigate the near-field radiative heat transfer (NFRHT) in complicated heterostructures consisting of two-dimensional and hyperbolic materials. Recent studies have reported that adding vacuum layers to multilayer structures can effectively enhance the NFRHT. Take the case of multilayer graphene/α-MoO₃ heterostructures: the effect of vacuum layers on these heterostructures has not been studied, and hence investigations on adding vacuum layers between graphene and α-MoO₃ layers should be emphasized. In this work, we conduct an investigation of the NFRHT between multilayer graphene/vacuum/α-MoO₃/vacuum heterostructures. Compared to unit graphene/α-MoO₃ heterostructures without vacuum layers, it is found that NFRHT between the heterostructures with vacuum layers can be suppressed to 49.1% when the gap distance is 10 nm, and can be enhanced to 16.3% when the gap distance is 100 nm. These phenomena are thoroughly explained by the coupling of surface plasmon polaritons and hyperbolic phonon polaritons. Energy transmission coefficients and spectral heat flux are analysed during the calculations changing chemical potentials of graphene, thicknesses of vacuum layers, and α-MoO₃ layers. This study is expected to provide guidance in implementing the thermal management of reasonable NFRHT devices based on graphene/α-MoO₃ heterostructures.