Antiferromagnetic Properties of Light Rare Earth Monochalcogenides

Magnetic investigation of monochalcogenides MeX where Me = Ce, Pr, or Nd and X = S, Se, or Te at 4°-1300°K was undertaken. Van Vleck's theory was used for describing experimental χ(T) dependences at T>500°K.

It has been observed that monochalcogendies formed by the ions with an odd number of electrons exhibit an antiferromagnetic ordering near ∼10°K in contrast to the monochalcogenides formed by the ions with an even number of 4f electrons (Pr³⁺, Sm²⁺) except PrS. An attempt to evaluate the parameters of the exchange interaction using molecular field approximation was made. In order to explain the χ(T) dependences obtained at T < 100°K the approximation which included crystal-field and exchange effects simultaneously is required.