Magnetic field dependence of the sensitivity of a type E (chromel–constantan) thermocouple

The effect of magnetic fields on the sensitivity of a type E thermocouple made from thin wires of chromel and constantan has been measured from 5 to 115 K in magnetic fields up to 9 T. In general, the field-induced change in sensitivity depends non-monotonically on the field. Above ∼7.4 K the sensitivity changes between 2% and −6% but increases sharply below this temperature even in weak magnetic fields of the order of 0.1 T. Magnetization measurements of the thermocouple elements indicate a ferromagnetic ordering in chromel and constantan at T ≈53 K and ≈19 K, respectively. The magnetization data for constantan suggest a re-entrant spin-glass transition at T ∼10 K.