HIGH-PRECISION MEASUREMENT OF ELECTRICAL-RESISTIVITY OF NICKEL NEAR THE FERROMAGNETIC PHASE-TRANSITION AT HIGH-PRESSURE

High-precision measurement of the resistance of nickel near its ferromagnetic phase transition at high pressure was done in a large volume hydrostatic cubic multiple-anvil pressure cell between 25 and 45 kbar. A real-time computer-controlled measurement system was developed to measure the resistance vs temperature and pressure. The values of the critical exponent alpha and amplitude ratio of the leading term A/A' are in good agreement with the results published by Ahlers and Kornblit from specific-heat measurement and by Kallback et al. in a resistance measurement at atmospheric pressure. They are found to be independent of pressure. The critical temperature T(c) increases linearly with pressure at a rate of 0.193+/-0.013 K/kbar. The amplitude ratio for the correction to scaling term D/D' has also been determined. There is considerable uncertainty in the measurement but the data may indicate a variation with pressure contrary to expectations of universality.