Submillimeter wave ESR of an S=1 bond alternating chain Ni 2(μ-C 2O 4)(μ-N 3)(dpt) 2(PF 6)

Abstract

Submillimeter wave ESR and magnetization measurements of Ni 2(μ-C 2O 4)(μ-N 3)(dpt) 2(PF 6) have been performed. This compound is one of the model substances of an S=1 antiferromagnetic chain with bond alternation. In the magnetization measurements, a step-like magnetization process has been observed at 4.2 K. The energy gap and the single-ion anisotropy are discussed from the magnetization using the S=1 spin dimer model. In the submillimeter wave ESR measurement, several absorption lines appeared as the temperature is increased from 4.2 K. However, such absorption lines can not be explained by the simple dimer model. The excitation gap is also discussed from the temperature dependence of the integrated intensity.