Dynamics of localized magnetic inhomogeneities in weak ferromagnets in a magnetic field in the presence of damping

Effects of an applied magnetic field and damping on the dynamics of localized magnetic inhomogeneities such as magnetization-reversal nuclei and interacting 180 degrees domain walls of like and unlike polarities have been investigated in weak ferromagnets. The investigations of the dynamics of magnetic inhomogeneities were carried out using an approximate method (developed in this work) of integrating a perturbed double sine-Gordon equation based on the Backlund transformation. It is shown that the presence of dissipation leads with time to a decrease in the period and amplitude of nonlinear oscillations of the magnetization-reversal nucleus that has the form of a breather. It has been established that the time of decomposition of such a center into two interacting 180 degrees domain walls of the same polarity increases with increasing damping parameter and decreases with increasing applied magnetic field. It has also been shown that in a field of the opposite direction there occurs annihilation of 180 degrees domain walls of like polarities which is accompanied, in the case of small attenuation, by a damped oscillating motion of domain walls and by a change of their polarity. The scattering of 180 degrees domain walls of the opposite polarities is accompanied by the formation of a 360 degrees domain wall, and their motion with respect to the common center can have the character of clamped oscillations or aperiodic damping, depending on the relationship between the field and the parameter of dissipation.