New low-frequency magnetic excitations in LaMnO3 single crystals

Microwave magnetic resonance of close to stoichiometric antiferromagnetic L aMnO3 - delta was investigated. LaMnO3 - delta single crystals were grown a nd a series of samples with a small oxygen excess and deficiency was prepar ed. Residual magnetization was observed for all samples in the series. The maximum value of the residual magnetic moment in the series of samples obta ined was 2.5% of the maximum possible value (4(mu B) for each Mn ion). An a bsorption line, whose angular and frequency dependences cannot be explained on the basis of a previously proposed [S. Mitsudo, et al., J. Magn. Magn. Mater. 177-181, 877 (1998)] model of two-sublattice antiferromagnet with "e asy axis" magnetic anisotropy (|| b) and canting of the magnetic sublattice s due to the Dzyaloshinskii-Moriya interaction, was observed in the experim ents performed on all samples in a series as well as on specially prepared ceramic samples with the same composition. It was inferred that the low-fre quency excitations in a system of ferromagnetic drops observed in [M. Henni on, et al., Phys. Rev. Lett. 81, 1957 (1998)] are observed in the experimen t. (C) 2000 MAIK "Nauka/Interperiodica".