EPR Study of the Quasi One-Dimensional Alternating Antiferromagnet CsFeS₂

Abstract

EPR line widths and the resonance field of CsFeS₂, the quasi one-dimensional alternating antiferromagnet, are measured as a function of the angle between the chain axis and the external applied field, and of the temperature over the range of 100 K and 500 K. The line widths are much broader than those of the similar compounds like KFeS₂, which is the usual quasi one-dimensional antiferromagnet; and the relaxation mechanism responsible for the extra line width is attributed to the singlet ground state of the alternating chain system.
Although the observed angular and temperature dependence of the line width could well be explained by the short time spin correlation due to the intra-chain exchange interaction; for the shift of the resonance field towards the higher field side irrespective of the applied field direction as temperature is lowered, no satisfactory explanation was found.