Direct imaging of the spatial and energy distribution of nucleation centres in ferroelectric materials.
Macroscopic ferroelectric polarization switching, similar to other first-order phase transitions, is controlled by nucleation centres. Despite 50 years of extensive theoretical and experimental effort, the microstructural origins of the Landauer paradox, that is, the experimentally observed low values of coercive fields in ferroelectrics corresponding to implausibly large nucleation activation energies, are still a mystery. Here, we develop an approach to visualize the nucleation centres controlling polarization switching processes with nanometre resolution, determine their spatial and energy distribution and correlate them to local microstructure. The random-bond and random-field components of the disorder potential are extracted from positive and negative nucleation biases. Observation of enhanced nucleation activity at the 90 composite function domain wall boundaries and intersections combined with phase-field modelling identifies them as a class of nucleation centres that control switching in structural-defect-free materials.
Jesse
Stephen
S
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Rodriguez
Brian J
BJ
Choudhury
Samrat
S
Baddorf
Arthur P
AP
Vrejoiu
Ionela
I
Hesse
Dietrich
D
Alexe
Marin
M
Eliseev
Eugene A
EA
Morozovska
Anna N
AN
Zhang
Jingxian
J
Chen
Long-Qing
LQ
Kalinin
Sergei V
SV