Anomalous magnetoresistance behavior of an insulating zirconium oxynitrideCernox (TM) thermometer

Zirconium oxynitride insulating films make excellent thermometry at 4K and above. The resistance is almost independent of magnetic fields up to 30T an d exhibits good temperature sensitivity and good reproducibility upon tempe rature cycling. However below 4K, this material exhibits an anomalous negat ive magnetoresistance (MR); for example at 86mK, the resistance decreases b y a factor of 24 in a 17T field as compared to its zero-field value. The ne gative magnetoresistace behavior is explained using a model proposed by Mov aghar, Schweitzer and Osaka. Fits to the negative MR data are good above 0. 3 K but become poorer at lower temperatures. (C) 2001 Elsevier Science B.V. All rights reserved.