Combined anomalous Nernst effect and thermography studies of ultrathin CoFeB/Pt nanowires

Abstract

Using electrical and thermal measurements, we present a method for characterising the anomalous Nernst effect (ANE) within nanoscale devices implementing perpendicular anisotropy materials. Perpendicularly magnetised CoFeB/Pt nanowires were fabricated in close proximity to Pt heater elements on an electrically insulating substrate. The voltages induced within the magnetic material as a result of the ANE were recorded for increasing heater powers, and for both out-of-plane saturated states of the device. Scanning thermal probe microscopy was used to map the temperature distribution within the region of the device at a range of heater powers. By analysing the results from each thermography measurement, it was possible to correlate the temperature gradient induced at the magnetic nanowire against the anomalous Nernst voltage measured within the device. For the particular material, geometry and substrate used, a Nernst coefficient value KN = 2.3 μV(K.T)-1 was calculated. This combination of measurements can provide a powerful tool to characterise the ANE within a number of nanoscale systems, a necessary task for the future implementation and optimisation of the effect within spin-caloritronic devices.