Ferroelastic Domain Collapse and Acoustic Emission: Non-equilibrium Behaviour of Multiferroic Materials

Nano-scale multiferroics often display sudden, jerky domain movements under weak external fields. These domain movements include retracting twin domains, kinks in domain walls, jamming between walls and changes in complex tweed patterns. The time evolution of such patterns under weak forcing may also contain additional continuous movements such as the propagation of a twin wall under stress. Other movements remain jerky such as pinning-depinning events that may lead to acoustic emission. We show that the probability density function, PDF, of the jerk distribution follows power law statistics at sufficiently low temperatures and thermally activated jumps at high temperatures. The overall Vogel Fulcher distribution of the PDF is explained by the mixing of thermal and athermal events during AE.