Orientation of the electric field gradient and ellipticity of the magnetic cycloid in multiferroic BiFeO3. Issue 3 (22nd January 2017)

• Record Type: Journal Article
• Authors: Pierzga, A.; Błachowski, A.; Komędera, K.; Ruebenbauer, K.; Kalvane, A.; Bujakiewicz-Korońska, R.
• Is Part Of: Philosophical magazine. Volume 97:Issue 3(2017)
• Page Start: 168
• Page End: 174
• Publication Date: 2017-01-22
• Subjects: Multiferroic -- Mössbauer spectroscopy -- crystal structure -- magnetic cycloid; Condensed matter -- Periodicals; Physics -- Periodicals; Matière condensée -- Périodiques; Physique -- Périodiques; 530.41
• DOI: 10.1080/14786435.2016.1248518
• Languages: English
• ISSNs: 1478-6435

Abstract

Abstract: The paper deals with the hyperfine interactions observed on the 57 Fe nucleus in multiferroic BiFeO3 by means of the 14.41-keV resonant transition in 57 Fe and for transmission geometry applied to the random powder sample. Spectra were obtained at 80 K, 190 K and at room temperature. It was found that iron occurs in the high-spin trivalent state. Hyperfine magnetic field follows distribution due to the elliptic-like distortion of the magnetic cycloid. The long axis of the ellipse is oriented along 〈1 1 1〉 direction of the rhombohedral unit cell. The hyperfine magnetic field in this direction is about 1.013 of the field in the perpendicular direction at room temperature. This ratio diminishes to 1.010 at 80 K. Axially symmetric electric field gradient (EFG) on the iron atoms has the principal axis oriented in the same direction and the main component of the EFG is positive. Our results are consistent with the finding that iron magnetic moments are confined to the crystal plane.