Metastable unipolar elastic deformation structures

The possibility of the formation of localized metastable elastic strain structures in a nonequilibrium paramagnetic crystal has been analyzed. Under the assumption that the process observation time is much longer than the characteristic phase relaxation times of a quantum transition between Zeeman sublevels but is shorter than the energy relaxation time, a new parabolic integrodifferential equation for the elastic strain has been derived. This equation includes nonlocal gain and nonlinearity compensating each other. A solution of this equation in the form of a localized unipolar structure traveling at a constant velocity has been found. This solution contains a continuous free parameter chosen as a time duration. When the time duration decreases, the amplitude of the metastable structure increases and the propagation velocity close to the linear speed of sound decreases. It has been shown that a medium does not return to the initial state after the passage of a local strain bunch.