Submillimeter and millimeter wave ESR measurements of frustrated triangular lattice substance InMnO 3

Spin dynamics of S=2 triangluar lattice antiferromagnet have been investigated by the submillimeter and the millimeter wave ESR measurements of polycrystalline samples of InMnO 3 . Single absorption line is observed in whole temperature range from 2.0 K to 265 K. The resonance field shifts due to the development of internal field are observed below 40 K. The spin dynamics of InMnO 3 will be discussed in connection with other triangluar lattice antiferromagnets.