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TT: Fachverband Tiefe Temperaturen
TT 13: Multiferroics I (jointly with DF, DS, KR, MA)
TT 13.2: Talk
Monday, March 14, 2011, 15:00–15:15, HSZ 04
Optical properties of BiCrO3 — •Cameliu Himcinschi1, Ionela Vrejoiu2, Silvia Bahmann1, Kannan Vijayanandhini2, Adreas Talkenberger1, Christian Röder1, Dietrich R.T. Zahn3, Alexei A. Belik4, and Jens Kortus1 — 1TU Bergakademie Freiberg, Institute for Theoretical Physics, D-09596 Freiberg — 2Max Planck Institute of Microstructure Physics, D-06120 Halle — 3TU Chemnitz, Semiconductor Physics, D-09107 Chemnitz — 4International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
Multiferroic materials that simultaneously show polarization and magnetization ordering are envisaged to play a significant role in developing devices with large magnetoelectric coupling. An interesting candidate for intrinsic multiferroism is BiCrO3 (BCO). In this work, the optical properties of polycrystalline BCO ceramics and epitaxial BCO films deposited on NdGaO3(110) substrates are investigated by Raman spectroscopy and spectroscopic ellipsometry. The spectral changes seen in temperature-dependent Raman measurements correlate well to a structural phase transition from a monoclinic structure (space group C2/c) to an orthorhombic structure (space group Pnma) at about 420 K. The room temperature dielectric function of a 55 nm thick BCO film deposited on NdGaO3 substrate is determined by analyzing ellipsometry data and exploited to estimate the BCO band-gap. The imaginary part of the dielectric function calculated by means of density functional theory shows good agreement with the experimental one. This work was supported by the German Research Foundation DFG HI 1534/1-1.