A MAGNETIC EQUATION OF STATE

In general, the intensity of magnetization, M, is dependent on both magnetic field, H, and on time and may be described in terms of a constitutive equation, or equation of state as dH = (1/chi)d M + LAMBDA-d ln M, where 1/chi = partial derivative H/partial derivative M\M and LAMBDA = partial derivative H/partial derivative ln M\M. Measurements have been made on Pr15Fe77B8 from which values of LAMBDA and chi as functions of M are derived using the constitutive equation. It is shown that chi is a function of M but is independent of M. At room temperature LAMBDA = (86.0 +/- 1.4) Oe over the magnetization range +300 to -500 G.