Leading researcher at EXAFS Spectroscopy Laboratory and deputy director for innovation of the ISSP UL Dr.phys. Andris Anspoks is a co-author of an article Dielectric response of BaTiO3 electronic states under AC fields via microsecond time-resolved X-ray absorption spectroscopy (DOI 10.1016/j.actamat.2021.116681) published in scientific journal Acta Materialia (IF 7,656) in April 2021 (volume 207). Co-authors are S. Kato, N. Nakajima, S. Yasui, S. Yasuhara, D. Fu, J. Adachi, H. Nitani and Y. Takeichi.
In the article, researchers describe that for the first time the dielectric response of a BaTiO3 thin film under an AC electric field is investigated using microsecond time-resolved X-ray absorption spectroscopy at the Ti K-edge in order to clarify correlated contributions of each constituent atom on the electronic states. Intensities of the pre-edge eg peak and shoulder structure just below the main edge increase with an increase in the amplitude of the applied electric field, whereas that of the main peak decreases in an opposite manner. Based on the multiple scattering theory, the increase and decrease of the eg and main peaks are simulated for different Ti off-center displacements. The results indicate that these spectral features reflect the inter- and intra-atomic hybridization of Ti 3d with O 2p and Ti 4p, respectively. In contrast, the shoulder structure is not affected by changes in the Ti off-center displacement but is susceptible to the effect of the corner site Ba ions. This is the first experimental verification of electronic contribution of Ba to polarization reversal.
