NanoESCA highlights

Ferroelectric domains

The objective of this work was to quantify the critical doping level and then to investigate the polarization dependence of the band structure at the surface of the doped ferroelectric domains.
J. E. Rault et al., Phys. Rev. Lett. 111, 127602 (2013).

An ideal ferroelectric (FE) must be an insulator to show a spontaneous polarization, however, recent theoretical and some experimental work suggests that a ferroelectric state can exist up to a certain critical doping level. Thus the possibility of coexistence of ferroelectricity and d electron occupancy opens the way to fascinating properties such as intrinsic multiferroicity, or field-induced metal to insulator transitions. Further progress in this field requires knowledge of the electronic structure which makes the decisive contribution to such functional properties.
The Energy-filtered PhotoEmission Electron Microscope (PEEM) at NanoESCA beamline was used to investigate in a single experiment the FE domain distribution by imaging the photoemission threshold, the momentum-resolved electronic properties using reciprocal space PEEM and the spatially-resolved chemical states micron-sized regions.

Using a combination of in situ UHV and oxygen annealing we can control the surface doping of BaTiO3 (001) which induces a paraelectric-ferroelectric phase transition in good agreement with theoretical predictions. Below the critical doping value, ferroelectric stability leads to domain formation with in- and out-of-plane polarizations reflected in the band structure symmetry. The unambiguous observation of domain ordering means that the link between band structure and polarization could be generalized to undoped ferroelectric systems.

Retrieve article

Polarization Sensitive Surface Band Structure of Doped BaTiO3(001); J. E. Rault, J. Dionot, C. Mathieu, V. Feyer, C. M. Schneider, G. Geneste, and N. Barrett;
Phys. Rev. Lett. 111, 127602 (2013);
doi: 10.1103/PhysRevLett.111.127602

Ultima modifica il Lunedì, 11 Novembre 2019 17:28