Electron Spin Resonance in Cr-Trimer Complexes

Electron spin resonance (ESR) and magnetic susceptibility of two chromium trimer complexes are investigated. Temperature dependence of magnetic susceptibility is well explained by antiferromagnetically coupled trimer model with two kinds of isosceles trimers in Cr-acetate and one isosceles trimer in Cr-propionate. A weak inter-trimer exchange interaction is found in Cr-propionate. The angular dependences of ESR signals are satisfactorily explained by the trimer model. Anomalous negative g-shift is observed in the field direction parallel to the trimer plane, which is attributed to the Dzyaloshinsky-Moriya interaction. A hybrid resonance of two doublets is found in Cr-acetate which is explained also by the Dzyaloshinsky-Moriya interaction.