SUBMILLIMETER-WAVE ESR MEASUREMENT OF LAMNO3

High-field magnetization measurements up to 40 T and submillimeter wav e ESR measurements in frequency range from 95 to 762 GHz have been per formed on a stoichiometric single crystal of LaMnO3. At 4.2 K, the ind uced magnetization curve shows nonlinear increase up to H-c = 21 T for H parallel to b and linear increase above H-c. This result suggests t hat the antiferromagnetic easy axis is the b-axis. For H parallel to b , several ESR lines are observed at 4.2 K. The obtained frequency-fiel d diagram shows these lines are the antiferromagnetic resonance with t he uniaxial anisotropy. (C) 1998 Elsevier Science B.V. All rights rese rved.