Phenomenological description of a giant temperature hysteresis of ultrasound velocity and internal friction in lanthanum manganite

We propose an explanation for the experimentally observed [1] giant temperature hysteresis of the ultrasound velocity and internal friction in single crystals of lanthanum manganite (La$_{0.8}$Sr$_{0.2}$MnO$_{3}$). The effect is interpreted within the framework of a phenomenological model based on the notion of two coexisting sublattices of the oxygen octahedra performing cooperative tilting-rotational oscillations in bistable potential fields.