BiFeO3 is one of the most attracting materials because it is the only known room-temperature multiferroic material. It has been studied by Raman spectroscopy extensively. We perform two-dimensional correlation spectroscopy (2D COS) and perturbation-correlation moving window two-dimensional correlation spectroscopy (PCMW2D) analysis on the temperature-dependent Raman spectra of a BiFeO3 single crystal. The two low temperature spin reorientation transitions around 135 K and 190 K are confirmed through the significant change in phonon peaks from PCMW2D correlation spectra. We also identify the origin of the mode at ~ 1255 cm−1, which has been controversial until now. In our 2D COS analysis, the intensity of this mode has a strong correlation with the intensity of 145 and 176 cm−1 phonons which correspond to the vibration modes of the Bi-O and Fe-O chemical bonds. We propose that the mode at ~ 1255 cm−1 is the two-phonon scattering of the 551 cm−1 mode assisted by the 145 −176 cm−1 phonons.
Bibliographical noteFunding Information:
This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grand number 103.02-2018.39 . I-S. Y. was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education ( 2021R1A6A1A10039823 ).
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- Multiferroic BiFeO
- Raman scattering, two-dimension correlation spectroscopy, perturbation-correlation moving window two-dimensional correlation spectroscopy