Development of a high pressure secondary gauge using AuCr spin-glass system

This paper offers an original approach to explain the metrologica! behavior of an Au + 6.4% at Cr pressure gauge under the influence of external parameters, at standard range of temperatures and for pressures up to 600 MPa. This is based on pressure and temperature effects on indirect RKKY and direct d-d exchange interactions between the spins associated with magnetic Cr impurities in spin-glass alloys such as AuCr. Special attention is paid to interpretation of the positive resistance-pressure coefficient, known in existing literature as an “abnormal” effect. Other metrological properties (i.e., perfect linearity, lack of hysteresis, temperature stability under low and high pressure) of pressure gauges made from AuCr spin-glass alloy are also discussed and explained in detail, together with some suggestions for future improvements. The paper also includes some original measurements of low temperature (77 K) effects in AuCr pressure gauges and offers an approach to understanding these effects in terms of magnetic properties of the alloy.