Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 38: Multiferroics I (DF with MA)
MA 38.5: Vortrag
Donnerstag, 10. März 2016, 10:50–11:10, H25
Influence of ferroelectric electron emission in BTO layer systems on measurements of core-level binding energies — •Paula Huth1, Martin Welke1, Alireza Bayat2, Karl-Michael Schindler2, Angelika Chassé2, and Reinhard Denecke1 — 1Wilhelm-Ostwald-Institut, Universität Leipzig — 2Institut für Physik, Martin-Luther-Universität Halle-Wittenberg
Barium titanate (BTO) is a well-known ferroelectric material with perovskite-like structure. During the phase transition from tetragonal to cubic crystal system at 120 ∘C, the spontaneous electrical polarization vanishes. In conventional x-ray photoelectron spectroscopy measurements, sudden shifts ("jumps") in core-level binding energies have been observed at the Curie temperature. This was proposed to originate from surface charge build-up[1], but by using high-kinetic energy XPS, the effect could be shown to occur for deeper layers and in the presence of covering non-conducting oxide layers, as well. Since the effect occurs at the ferroelectric-to-paraelectric phase transition, ferroelectric electron emission[2] is proposed as origin. Iron and Cobalt layers of different thicknesses have been prepared in-situ on BTO(001), to show that the effect vanishes if a conducting layer is present. Such core-level shifts have been found for all elements in BTO, except in the presence of thick metal overlayers. Additionally, a general difference of the electronic binding energy between the tetragonal and the cubic phase has been observed and confirmed by DFT calculations. [1] L. Makhova et al.: Phys. Rev. B, 83 (2011) 11540. [2] G. Rosenman et al.: J. Appl. Phys., 88 (2000) 6109.