The triangular antiferromagnet CsFeBr3, which has the spin singlet ground state due to the large single ion anisotropy of Fe2+ ions, shows the field-induced magnetic ordering for B||c. Submillimeter and millimeter wave ESR measurements of CsFeBr3 have been performed at 2 K. Several absorption lines were observed below the ordering field 5 T which is in the paramagnetic region. Temperature dependence of ESR absorption lines for paramagnetic region shows the decrease of intensity as the temperature is increased. It suggests that the observed ESR absorption lines come from the ground state. Changes of the ESR modes at 2 K were observed at the field corresponding to the antiferromagnetic gap of 2.89 T. The results are discussed in connection with the theory of the gap system.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering