Submillimeter and millimeter wave ESR measurements of (DMET)2FeBr4 below TN

Abstract

Submillimeter and millimeter wave ESR measurements of (DMET) 2 FeBr 4 , which has π-d interaction between quasi 1D π-electrons and localized d-electrons, have been performed at 2.1K. Frequency-field relation below the saturation field B=7T agrees with antiferromagnetic resonance (AFMR) modes with the uniaxial anisotropy. However, AFMR modes above B,=7T for B//a and B//c do not follow the AFMR modes with the same uniaxial anisotropy. As the anomalies in the field dependence of g-value coincide with the previous magnetoresistance measurement, the ESR result also suggests the existence of strong π-d interaction.