# Avalanche criticality during ferroelectric switching

Blai Casals

Field induced domain wall displacements dene ferroelectric hysteresis loops, which are at the core of piezoelectric, magnetoelectric and memristive devices. These col-lective displacements are scale invariant jumps with avalanche characteristics [1]. Here, we analyse the spatial distribution of avalanches in ferroelectrics with different domain and transformation patterns: Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) contains complex domains with needles and junction patterns, while BaTiO3 has parallel straight domains. Nevertheless, their avalanche characteristics are indistinguishable. The energies, areas and perimeters of the switched regions are power law distributed with exponents close to predicted mean field values. At the coercive field (Ec), the area exponent decreases, while the fractal dimension (HD) increases (see gure 1). This fine structure of the switching process has not been detected before and suggests that switching occurs via criticality at the coercive field with fundamentally different switching geometries at and near this critical point. We conjecture that domain switching process in ferroelectrics is universal at the coercive field.

[1] Blai Casals, Guillaume F. Nataf, David Pesquera, Ekhard K. H. Salje. Avalanches from charged domain wall motion in BaTiO3 during ferroelectric switching, APL Mater. 8 011105 (2020).