Susceptibility of spin-fluctuation compounds in high magnetic fields

The differential susceptibilities of the spin-fluctuation compounds TiBe2, UAl2, UCo2, and UPt3 have been measured at low temperatures as a function of magnetic field up to 40 T. A systematic relation is observed between the signs of the second derivatives of the susceptibility with respect to field and temperature. A characteristic field H/sub sf/ and a characteristic temperature T/sub sf/ are defined by the inflection points in the chi(H) and chi(T) curves, respectively. It turns out that μ/sub B/H/sub sf/ is of the order of kT/sub sf/