Probing the role of single defects on the thermodynamics of   electric-field induced phase transitions
  The kinetics and thermodynamics of first order transitions is universally controlled by defects that act as nucleation sites and pinning centers. Here we demonstrate that defect-domain interactions during polarization reversal processes in ferroelectric materials result in a pronounced fine structure in electromechanical hysteresis loops. Spatially-resolved imaging of a single defect center in multiferroic BiFeO3 thin film is achieved, and the defect size and built-in field are determined self-consistently from the single-point spectroscopic measurements and spatially-resolved images. This methodology is universal and can be applied to other reversible bias-induced transitions including electrochemical reactions. 
S.V. Kalinin, S. Jesse, B.J. Rodriguez, Y.H. Chu, R. Ramesh, E.A.   Eliseev, and A.N. Morozovska