Thermal imaging of anomalous Ettingshausen effect at low temperatures using infrared lock-in thermography

Abstract

Thermal imaging technology has significantly advanced the fields of thermal engineering and fundamental physics by enabling precise and non-contact temperature measurements. In the field of spin caloritronics, an active infrared emission microscopy approach based on lock-in thermography (LIT) has significantly advanced the study of thermoelectric and thermal transport phenomena in magnetic materials and their hybrid structures; however, its measurements have been largely limited to room temperature and above. Here, we report on the measurements of transverse thermoelectric conversion in a magnetic material, the anomalous Ettingshausen effect (AEE), below room temperature using the LIT technique. Although the infrared emission decreases with decreasing temperature, the high temperature resolution of LIT allows to observe the AEE-induced temperature modulation in a ferromagnetic Heusler alloy Co2MnGa slab down to 200 K and reliably quantify the anomalous Nernst coefficient down to around 240 K. The methodology demonstrated in this work will pave the way for further developments in both fundamental research and practical applications in spin caloritronics.