Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 58: Multiferroics II (organized by MA)
TT 58.5: Vortrag
Mittwoch, 2. April 2014, 10:30–10:45, HSZ 04
The influence of strain on the optical properties of pseudo-tetragonal BiFeO3 thin films — •Cameliu Himcinschi1, Akash Bhatnagar2, Andreas Talkenberger1, Dietrich R.T. Zahn3, Jens Kortus1, and Marin Alexe2, 4 — 1TU Bergakademie Freiberg, Institute of Theoretical Physics, D-09596 Freiberg, Germany — 2Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany — 3Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany — 4Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
Tetragonally distorted BiFeO3 recently attracted a lot of attention because of its interesting multiferroic properties and the larger spontaneous polarization as compared to its rhombohedral counterpart. Highly strained (when grown on LaAlO3 substrates) and nearly pseudomorphic (when grown on TbScO3 substrates) BiFeO3 films were deposited by pulsed laser deposition. The symmetry of the tetragonally distorted BiFeO3 films is discussed based on polarisation dependent Raman measurements and the comparison with Raman spectra measured for films deposited on TbScO3. The evaluation of ellipsometric spectra reveals that the films deposited on LaAlO3 are optically less dense and the dielectric function is blue-shifted by more than 0.3 eV as compared to the films deposited on TbScO3. By analyzing the absorption edge using a bandgap model, bandgaps of 3.10 eV and 2.75 eV were determined for the films deposited on LaAlO3 and TbScO3, respectively. This work is supported by the German Research Foundation DFG HI 1534/1-1.