PHASE-DIAGRAM OF FE(1-X)COXCL2 - RANDOM MIXTURE OF 2 ANTI-FERROMAGNETS WITH COMPETING SPIN ANISOTROPIES

Concentration vs transition temperature phase diagram of a random mixture of two anisotropic antiferromagnets, FeCl2 and CoCl2, is obtained from the measurement of the susceptibility on the single crystals. Two distinct critical points, one along the c-axis and the other in the c-plane, are observed for the respective concentrations between x = 0.264 and x = 0.481. Three kinds of ordered phases, namely, Fe-rich and Co-rich antiferromagnetic phases and a new phase are found. The phase diagram shows a tetracritical point as well. A hump is observed in the temperature dependence of the susceptibility along the c-axis (c-plane for x ≲ 0.3) near the ordering temperature occuring in the c-plane (c-axis for x ≲ 0.3). © 1979.