Breather induced modification of the speed of sound

Abstract

The modification of the speed of sound induced by the presence of breathers in a quasi-one-dimensional magnetic chain is examined in the framework of the sine-Gordon model. Within the pseudoharmonic phonon approximation it was found that the spin-phonon interaction could have a significant influence on the phonon frequencies, and it consequently leads to the modification of the speed of sound which, in the case of breathers, shows quite different magnetic field and temperature behavior when compared to the case of the linear excitations and solitons. An interesting possibility of an indirect experimental examination of the breathers arises from these predictions.