Near-Field Thermal Radiation between Nanostructures of Natural Anisotropic Material

While nanostructures exhibit remarkable optical and thermal properties, including super-Planckian emission beyond the black-body limit, they are usually made of isotropic materials; anisotropic nanostructures are rarely considered, despite their potential for applications. Investigating near-field thermal radiation between gratings of natural anisotropic graphite, the authors find that nanopatterning enhances heat flux dramatically, due to the excitation of anisotropic surface modes not possessed by plain graphite. This deepened understanding could open routes to more efficient thermal management and thermophotovoltaic energy conversion.