Temperature dependence of the Hall coefficient of sensitive layer materials considered for DEMO Hall sensors

•The sensitivity of Hall sensors always depends on temperature.•Based on the required high operating temperatures, metal Hall sensors are considered.•Comparison of bismuth, antimony, molybdenum, tantalum, gold, copper, and platinum.•Bismuth and antimony provide high sensitivity strongly dependent on temperature.•Molybdenum and tantalum provide low sensitivity almost independent on temperature. The Hall sensors as a part of the DEMO magnetic diagnostics will perform an absolute measurement of the steady-state magnetic field. However, the magnitude of the Hall coefficients generally depends on the temperature. The paper presents an evaluation of the temperature dependencies of the Hall coefficients of materials considered for the DEMO Hall sensors from room temperature up to 550 °C. The results show that tantalum or molybdenum sensors would be the best in terms of the low temperature dependence of their Hall coefficient. Bismuth and antimony offer a Hall coefficient several orders of magnitude higher than other considered materials, but strongly temperature-dependent, while usability of bismuth is limited by its melting temperature of 271.4 °C. The gold, copper and platinum sensors feature modest temperature dependence of their Hall coefficients which might result in the necessity of dedicated temperature monitoring of these sensors in order to achieve sufficient measurement accuracy, similarly to bismuth and antimony.