Magnetoacoustic resonance on nuclear spin waves in the cubic antiferromagnet RbMnF3

Magnetoacoustic resonance on nuclear spin waves is measured in the cubic an tiferromagnet RbMnF3. A resonance change with respect to a constant magneti c field H-0 with maximum damping at H-0 approximate to 4 X 10(3) Oe is obse rved in the amplitude of an acoustic pulse passing through a sample owing t o excitation of nuclear spin waves under nuclear magnetoacoustic resonance conditions. A study of the angular dependence of the damping revealed a 90 degrees periodicity consistent with the fact that the [001] direction, arou nd which the rotation takes place, is a four-fold axis of the crystal. An a nalysis of the dispersion law for nuclear spin waves shows that longitudina l ultrasound propagating along the [001] axis perpendicular to H-0 excites a branch of nuclear spin waves whose frequency depends on the magnitude of the constant magnetic field. (C) 1999 American Institute of Physics. [S1063 -7834(99)02102-4].