A simple model of thermoelastic heat switches and heat transistors

© 2017 Author(s). By combining differences in thermal conductivity and in thermal expansion coefficients of two materials A and B in series, but not physically attached to each other, a thermal switch or a thermal transistor may be achieved, depending on the relative role of near-field contribution to the radiative heat transport across the occasional gap between A and B. Indeed, when the temperature gradient becomes high enough, the contraction of the colder part may be bigger than the expansion of the hotter one, and a spatial gap appears between both materials. When the radiative heat transport across the gap is described by the Stefan-Boltzmann law, the drop in heat transport is very steep, and the system behaves as a thermal switch. In contrast, if the near-field contribution is dominant, negative differential thermal conductivity may arise, leading to the possibility of a thermal transistor.