Normal-Metal–Superconductor Near-Field Thermal Diodes and Transistors

Abstract

In recent years there has been a number of proposals of thermal devices operating in the near-field regime that make use of phase-transition materials. Here, we present a theoretical study of near-field thermal diodes and transistors that combine superconducting materials with normal (nonsuperconducting) metals. To be precise, we show that a system formed by two parallel plates made of Nb and Au can exhibit unprecedented rectification ratios very close to unity at temperatures around the Nb superconducting critical temperature and for a wide range of gap size values within the near-field regime. Moreover, we also show that a superconducting Nb layer placed between Au plates can operate as a near-field thermal transistor where the amplification factor can be greatly tuned by varying different parameters such as the temperature and thickness of the Nb layer or the distance between the Nb layer and the Au plates. Overall, our work shows the potential of the use of superconductors for the realization of near-field thermal devices.

Smart thermal management with near-field thermal radiation

“…Thanks to this transition rectification coefficients higher than 70% have been predicted and highlighted in far-field regime [27,37,38] with a temperature bias ∆T < 50 K and values around 90% have been observed in near-field regime [29,[39][40][41]. Furthermore, materials undergoing a normal-metal-superconductor transition [42][43][44][45][46] have also been considered to design radiative thermal rectifiers operating at cryogenic temperatures with similarly good performances.…”

“…In this temperature range, the thermal resistance R = ( ∂ϕ D ∂T G ) −1 defined as the variation of flux ϕ D received by the drain with respect to the gate temperature T G is negative [98]. Under these conditions, the amplification factor of the transistor A =| ∂ϕ D ∂ϕ G | can be higher than unity [46,97]. By using single or combining several radiative transistors, logic gates have been designed [99,100] to perform a Boolean treatment of information with heat exchanged in near-field regime.…”

Radiative thermal rectification in many-body systems

“…This thermal rectification exploits the thermal dependence of optical properties of the materials in interaction [79][80][81][82], which naturally breaks the symmetry in the heat transport when the sign of the temperature gradient between the two solids is changed. In addition, a large asymmetry in the heat transport was reported in systems made with materials undergoing a phase change, such as metal-insulator transition materials [83][84][85][86][87][88][89][90][91][92][93][94][95][96] and normal metal-superconductor transition materials [97][98][99]. However, this strong rectification occurs only close to the critical temperature of these materials.…”

Radiative thermal rectification in many-body systems

“…This thermal rectification exploits the thermal dependence of optical properties of the materials in interaction [78][79][80][81], which naturally breaks the symmetry in the heat transport when the sign of the temperature gradient between the two solids is changed. In addition, a large asymmetry in the heat transport has been reported in systems made with materials undergoing a phase change, such as metalinsulator transition materials [82][83][84][85][86][87][88][89][90][91][92][93][94][95] or normal metalsuperconductor transition materials [96][97][98]. However, this strong rectification only occurs close to the critical temperature of these materials.…”