Magnetization of Nickel near its Critical Temperature

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Abstract
Magnetic properties of a single‐crystal sphere of nickel as a function of temperature and applied field have been measured in the critical region. The dependent variable, directly measured, is proportional to MV/B where B is the applied field and MV is the magnetic moment of the sphere in the direction of B. Below TC and for B Ms(T) /3, where Ms(T) is the spontaneous magnetization, M/B=3/4π. This serves as an absolute calibration of the measurement. Three types of data have been taken: (1) M/B at constant T for 20 G<BT/TC=3×10−4 from TC−0.01 TC to TC+0.01 TC; (2) M/B at constant B in steps of ΔT/TC=3×10−6 from TC−0.01 TC to TC+0.01 TC for B=20, 240, 500, and 5000 G; (3) B at constant M/B in various steps of ΔT/TC for various values of M/B near 3/4π and near 0.2. From a partial analysis of the data we find an approximate equation of state for Ni. It is: (H/M)0.764=(T−TC)/0.309+ |M/39.5| 2.59. This equation of state fits well to the data of Weiss and Forrer also. But it does not fit for small values of H/M. The initial susceptibility fits better to (H/M)0.764=(T−TC)/0.345.