Raman Imaging Approach to the Study of Ferroelectric Domains and Raman Spectra of Multiferroic Boracites

• Authors: M. Iliev , V. Hadjiev , J. Íñiguez , J. Pascual
• Languages of publication: EN

Abstracts

EN

The boracites with general formula M_3B_7O_{13}X (M = divalent metal, X = Cl, Br, I), shortly denoted as M-X, are among the first known multiferroic materials. They exhibit a sequence of transitions from the high temperature paraelectric cubic phase to ferroelectric orthorhombic, monoclinic, trigonal phases, and finally to a monoclinic phase at low temperatures, where both ferroelectric and magnetic orders coexist. The lattice dynamics of boracites has been scarcely studied with the Raman spectroscopy, the main problem with non-cubic phases being the coexistence of twin variants with different crystallographic and polarization orientation. In this work, on the example of Co_3B_7O_{13}Cl (Co-Cl), Co_3B_7O_{13}Br (Co-Br) and Ni_3B_7O_{13}Br (Ni-Br) we demonstrate that using the Raman microscopy imaging one can visualize the twin variants, follow their transformation through the crystallographic transitions, obtain Raman spectra from untwinned domains in exact scattering configurations, determine the Raman mode symmetries, and assign Raman lines to definite atomic motions. The effects of structural transitions and elemental substitution are discussed in close comparison with results of ab initio calculations of the phonon structure of the cubic phase.

Keywords

EN

78.30.-j; 77.84.Bw

Discipline

• 77.84.Bw: Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
• 78.30.-j: Infrared and Raman spectra(for vibrational states in crystals and disordered systems, see 63.20.-e and 63.50.-x, respectively; for Raman spectra of superconductors, see 74.25.nd)

• Journal: Acta Physica Polonica A
• Year: 2009
• Volume: 116
• Issue: 1
• Pages: 19-24

Dates

published

2009-07

Contributors

author

M. Iliev

• Texas Center for Superconductivity, University of Houston, Houston TX 77204-5002, USA

author

V. Hadjiev

• Texas Center for Superconductivity, University of Houston, Houston TX 77204-5002, USA

author

J. Íñiguez

• Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), 08193 Bellaterra (Barcelona), Spain

author

J. Pascual

• Institut Català de Nanotecnologia (ICN) Edifici CM7, Campus de la UAB 08193 Bellaterra (Barcelona), Spain
• Departament de Física Edifici Cn Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain

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Identifiers

DOI

10.12693/APhysPolA.116.19