ANOMALOUS ANISOTROPY IN THE RCO4B COMPOUNDS

The magnetic anisotropy of YCo4B determined by the singular point dete ction (SPD) method and magnetization measurements over a large range o f temperature is reported. The anisotropy energy of CeCo4B estimated b y magnetization measurements is one order of magnitude larger than tho se of compounds with Y, La, or Gd. The temperature dependence of aniso tropy energy in YCo4B is discussed in the light of the temperature var iation of the c/a ratio and the giant anisotropy of CeCo4B is presumed to be due to the itinerant character of the 4f states in the compound .