Strain‐Induced Large Anomalous Nernst Effect in Polycrystalline Co2MnGa/AlN Multilayers

Abstract

AbstractThe anomalous Nernst effect (ANE), one of the thermoelectric effects in a magnet, is recently attracting growing interest with its potential for the next generation high‐efficiency energy‐harvesting applications. However, the reported thermoelectric conversion efficiencies with ANE are small compared to those with Seebeck effect, which hampers its practical application. Unlike the intensive effort of seeking novel materials with large intrinsic ANE, here a new pathway is proposed to enhance the ANE by exploiting the strain induced in a multilayer structure. A large anomalous Nernst coefficient of 4.9 µV K−1 is achieved for a polycrystalline Co2MnGa/AlN multilayer film deposited on an amorphous substrate, which is larger than 3.8 µV K−1 for a polycrystalline Co2MnGa single layer film. The enhanced ANE is attributed to the effect of interfacial strain on the Seebeck coefficient, which is barely discussed yet. Since the AlN layer is available on any substrate materials, even on a flexible polyimide substrate large ANE is successfully achieved for the Co2MnGa/AlN stack. The findings and demonstration have opened a way to develop the ANE‐based potential applications.