Diverging Relaxation Times of Domain Wall Motion Indicating Glassy Dynamics in Ferroelastics

Single crystals of PbZrO3 and LaAlO3 have been studied by Dynamic Mechanical Analysis measurements in the low frequency range f = 0.02-50 Hz. The complex Young's modulus exhibits a quite rich behavior and depends strongly on the direction of the applied dynamic force. The low frequency elastic response in the [110]c-direction is dominated by domain wall motion, leading to a superelastic softening effect below Tc. With decreasing temperature this superelastic softening gradually disappears, due to an increasing relaxation time τDW of domain wall motion. For PbZrO3, τDW seems to diverge at a finite temperature TVF, indicating glassy behavior of domain freezing.