Direct determination of magnetic anisotropy in S=1 bond alternating system by high field ESR

Abstract High field ESR measurements were performed on an S=1 chain system with bond alternation. Based on the simple dimer model, we estimated the single ion anisotropy as D/k B =9.7 K and E/k B =0.4 K . Applying the numerical calculation results including the dimer–dimer interaction, the estimated value of D was corrected to be 12.6 K , which agrees with that deduced from the susceptibility and the magnetization data.