Percolating cermet thin-film thermistors between 50 mK–300 K and 0–20 T

Abstract

Cermet thin-film resistors consisting of roughly 50-Å Pt or Mo particles in Al2O3 at compositions just below the percolation transition provide a number of useful features for thermometry. These include: continuous sensitivity from at least 50 mK to 300 K, adjustable temperature dependence, low heat capacity, small size, excellent stability, and a saturable magnetoresistance. The fabrication, microstructure, and temperature dependence of the resistance and magnetoresistance of these materials are described. We find poor agreement with existing theories of conduction in granular materials.