Surface Proximity Effect, Imprint Memory of Ferroelectric Twins, and Tweed in the Paraelectric Phase of BaTiO₃

For post-CMOS electronics applications using ferroic materials, the surface can play a crucial role. Non-invasive techniques are required to study the chemistry and electronic structure underlying their unique electrical properties. The sensitivity of photoemission (PEEM) electron microscopy to local surface potential, chemistry and electronic structure makes it a useful tool for probing the ferroic surfaces.
We present a PEEM study of the evolution of the domain structure in BaTiO₃(001) through the phase transition. At room temperature, in- and out-of-plane polarized domains are present with ferroelectric and ferroelastic domain walls. Adsorbate screening results in inversion of the electrostatic surface potential contrast. Domain-related structure above the Curie temperature (T_C) is observable. Ferroelectric memory persist up to 550 K. The domain-like structures above T_C may be related to a combination of atomic relaxation, adsorbates and oxygen vacancies. Finally, we present some first results of PEEM imaging of domain wall creep at the surface of BaTiO₃ around T_C.