Solid state thermal rectification by chemical pressure tuning of magnetic properties in perovskites

From an efficiency framework, waste heat generation and accumulation place significant limitations on how systems ultimately perform. Particularly, heat buildup leads to a significant loss of efficiency and subsequently system failure. In addition, current insulation and heat removal elements for supporting reliability and efficiency are robust and high power consumption systems that are based entirely on linear thermal elements instead of non-linear elements that would allow a unidirectional heat regulation process, thereby avoiding heat accumulation. In this sense, thermal rectifiers have recently attracted considerable interest due to their ability to manage heat unidirectionally. In this work, with the aim of exploring the potential of perovskites in thermal rectification, the magnon mediated thermal transport in the system La0.7Sr0.3Mn1-xCoxO3 (0 < x < 0.1) obtained by the solid-state ceramic route is investigated. Interestingly, results shows that thermal conductivity and Curie temperature substantially decreases with increasing of Co contents, which is attributed to the fact that positive chemical pressure is created due to smaller Co atoms take the place of some of the Mn atoms in the perovskite, shrinking the crystal structure. Taking advantage of those granted features, two-segment thermal diodes based on La0.7Sr0.3Mn1-xCoxO3/SiO2 have been implemented as a proof of concept devices. Experimental thermal transfer characteristics reveal that thermal diodes have markedly a nonlinear heat transport with rectification factors up to 2.3, meaning that devices control the heat flow via the deactivation of magnons through the Curie temperature; which in turn, controls accurately the on state of the device.