The state excited from the ground singlet of Co3+ in LaCoO3 was investigated by submillimeter-wave electron spin resonance (ESR) measurements. Clear ESR signals with zero-field splitting were observed above 20 K for the first time. The activation energy is estimated to be △≈140 K, from the temperature dependence of the signal intensity and the resonance-width. The frequency and angular dependence of the signals were successfully analyzed by an effective spin-Hamiltonian with uniaxial anisotropy. The parameters obtained are g∥=3.35, g⊥=3.55, and D=+4.90 cm-1 for the effective spin S= 1. The results reveal that the first excited state is a triplet with a zero-field splitting of Co3+ in LaCoO3.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2002 Sept 1