Antiferromagnetic resonance spectrum in LaMnO3

The substantially noncollinear magnetic structure realized in LaMnO3 in an external magnetic field is investigated, and the frequency-field diagram of the magnetic eigenmodes of the system is obtained. It is shown that neglect of the Dzyaloshinskii interaction, a measure which a number of authors contend is justified because the corresponding constants of the spin Hamiltonian are small compared to the anisotropy, leads to an incorrect description of the dynamics of the system. (C) 2003 American Institute of Physics.