“…In contrast to the DL, the SIT occurs only after time τ from the field application and can exist for a long time (mach larger than τ) [17,19] and, consequently, has more chances to be observed experimentally. Beyond the τ-approximation, the values of the field at which the DL and the SIT occur can be quite different [8,9,17]. Moreover, at non-periodic biharmonic field, the DL exists and the SIT does not [17].…”