Abstract: Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.

Key words: intrinsic localized mode, antiferromagnet, magnon