New Kinds of Acoustic Solitons

We find that the modified sine-Gordon equation belonging to the class of the soliton equations describes the propagation of extremely short transverse acoustic pulses through the low-temperature crystal containing paramagnetic impurities with effective spin S=1/2 in the Voigt geometry case. The features of nonlinear dynamics of strain field and effective spins, which correspond to the different kinds of acoustic solitons, are studied.