Magnetic Properties of Layer-Type Compounds TlGdS2and TlGdSe2

Ternary thallinm lanthanide dichalcogenides TILnX2 (X = S, Se, or Te; Ln = lanthanide, except Ce and Pr) crystallize in the rhombohedral structure of α-NaFeO 2 type (R3m).Their crystal lattice consists of the layers of Ln3 + ions separated by three layers of the non-magnetic ions (-Ln-X-Tl-X-Ln-).The magnetization was measured in the field range 0-14 T. The molecular field constants λ m were estimated by fitting the Brillouin function to the experimental magnetization plots.The difference between the λ m values for the thallium gadolinium sulphide and the selenide corresponds to the different character of Gd-S and Gd-Se bonds and gives rise to the different J 1 and J2 exchange integrals.