Anomalous Nernst Effect em fitas magnéticas à base de Co produzidas por Melt Spinning

Abstract

The Anomalous Nernst Effect (ANE) is a thermomagnetic effect with great applicability for the development of sensors with low energy consumption and reduced sizes for use in different types of systems. In this context, studies have been conducted to sevaluate the magnetic properties of several metal alloys in order to verify their behavior when subjected to the necessary conditions for the observation of ANE. Although the study of this effect has been done recurrently for decades, few references can be found in the literature about its occurrence in amorphous magnetic tapes, so they represent a little explored field and potentially of great interest for the development of magnetic sensors or thermopiles. Based on this premise, the present work proposes to make a comprehensive and in-depth characterization regarding the magnetic and thermomagnetic properties of Fe3Co67Cr3Si15B12 ribbons produced via Melt Spinning. The thickness and width of the strips have been measured and verified in previous studies, as well as their Curie temperature and crystallization temperature, so this work is dedicated to measuring the magnetization of the strips and the ANE signal that can be obtained from them. Regarding the magnetization measurements, a VSM device was used and measurements were made at an interval of 90° to observe possible variations in the magnetization curves and the results revealed the presence of a shape anisotropy in the ribbons that, despite not being of a high intensity due to the characteristic amorphous structure of the ribbons, was still enough to interfere with the measurements. The ANE measurements were made using a homemade equipment using an electromagnet to generate the magnetic field and a micro-Peltier to generate the temperature gradient necessary for the observation of the effect; they revealed a linear dependence of the observed voltage in relation to the temperature gradient imposed on the ribbons and the shape of the ANE curves showed great similarities with the curves obtained in the VSM, pointing to the characteristic relationship between the ANE and the magnetization. Finally, the behavior of the ANE was observed for the parallel association of multiple samples, an important step for the study of the applications of Fe3Co67Cr3Si15B12 ribbons as thermopiles.