Magnetically Activated Flexible Thermoelectric Switches Based on Interconnected Nanowire Networks

The use of the spin degree of freedom in thermoelectric conversion offers new functionalities for electronic devices powered by waste heat and a promising solution for sustainable technologies. Here, thermocouples formed from two dissimilar arrays of interconnected magnetic nanowires embedded in a polymer film are used to realize flexible thermoelectric switches providing optimal magnetic‐field‐induced control of the sign and magnitude of the thermopower. By finetuning the composition of the homogeneous and multilayered nanowires forming the thermocouple legs, an ideal on/off ratio in the switching of the thermoelectric output voltage, or a simple sign reversal can be achieved in the presence of a magnetic field. This work paves the way for flexible spin‐caloritronics devices exploiting residual thermal energy for the development of thermally activated sensors and logic devices. The development of thermoelectric devices powered by waste heat is promising from a sustainable development perspective. Making them flexible so that they can conform to complex surfaces or the human body is a key advantage. Here, magnetically driven thermoelectric switches are demonstrated using flexible films of magnetic nanowire arrays, allowing fine control of the magnitude and sign of the thermopower.