Title: Magnetic-coupled phase anomaly in mixed-phase BiFeO3 thin films
Authors: Huang, Yen-Chin
Liou, Yi-De
Liu, Heng-Jui
Lee, Hsin-Hua
Chen, Yi-Chun
Chu, Ying-Hao
材料科學與工程學系
Department of Materials Science and Engineering
Issue Date: 1-Aug-2017
Abstract: The rich phase diagram of rhombohedral (R)-like and tetragonal (T)-like monoclinic polymorph in strained BiFeO3 (BFO) films brings on various functionalities. Finding correlations of physical ordering parameters in this system is generally difficult because T-like and R-like phases are undistinguishable in many aspects. In this study, the magnetic-coupled structural transitions of the mixed-phase BFO at low temperatures were investigated by atomic force microscopy (AFM), X-ray diffraction (XRD), and Raman spectroscopy. To resolve the complexity resulted from the similarity between T-like and R-like phases, we analyzed the Raman spectra on a micro-scale region with various T/R ratios, which is in situ manipulated by an AFM tip carrying a dc bias. Phonons of T-like and R-like phases were thus successfully separated. Based on temperature-dependent XRD and resolved Raman spectra, we observed two isostructural transitions at around 225 K and 150 K, and they are strongly correlated with the magnetic ordering in the mixed-phase BFO film. Moreover, through the effective spin-lattice coupling, the evolution of the T/R polymorph is changed by the magnetic cooling process at low temperatures. This study provides a pathway to modulate phonon behaviors by magnetic fields in a highly strained system. (C) 2017 Author(s).
URI: http://dx.doi.org/10.1063/1.4990138
http://hdl.handle.net/11536/145991
ISSN: 2166-532X
DOI: 10.1063/1.4990138
Journal: APL MATERIALS
Volume: 5
Issue: 8
Begin Page: 0
End Page: 0
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