Theoretical study of electrical oscillation effect in Sn₂P₂Se₆ single crystals with incommensurate phase

Abstract

For the ferroelectric (FE) semiconductor Sn₂P₂Se₆ with the incommensurate (IC) phase the theoretical study of long-term low-frequency (10 Hz-1 kHz) electric oscillations appeared in a deep IC-phase and acquired the relaxation character in the vicinity of IC-FE phase transition has been performed. A bifurcation analysis was performed by the examination of the evolution equation for the one-dimensional case in the first harmonic approximation with linearization near T_c. Results point out the existence of bifurcation of “saddle → stable focus → stable node” type. The oscillatory solution of the nonlinear evolution equation has been found in the region, where we can neglect the relaxation processes. The dispersion relation for the amplitude and the frequency of oscillations has been discussed.

Key Words:

• incommensurate phase
• nonlinear evolution equation
• dispersion relation