2-DIMENSIONAL SOLITONS IN THE CLASSICAL HEISENBERG-ANTIFERROMAGNET WITH NONMAGNETIC IMPURITIES

Experimental evidence is presented for the existence of nonlinear loca lized spin excitations (solitons) in the classical two-dimensional Hei senberg magnet doped with nonmagnetic impurities. These solitons are s hown to provide the dominant mechanism for spin relaxation in electron paramagnetic resonance linewidths immediately above the ordering temp erature for layered Mn compounds with a small impurity concentration. The new gapless excitations are pinned by the nonmagnetic impurities t hereby becoming topologically unstable and lower in energy than the no nlinear excitations (skyrmions) that may exist in the pure material. C oncentration-dependent results preclude a spin-wave mechanism for this effect. (C) 1996 American Institute of Physics.