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Abstract

Investigation of High Pressure Phase Transition by Means of Infrared Spectroscopy in the Cairo Frustrated Pentagonal Magnet Bi2Fe4O9 †

1
Ligne AILES-Synchrotron SOLEIL, 91190 Gif-sur-Yvette CEDEX, France
2
INAC/MEM, CEA-Grenoble, 38042 Grenoble, France
3
Institut Néel, CNRS&University, Grenoble Alpes, 38042 Grenoble, France
4
Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA
5
ICREA, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
6
Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
*
Author to whom correspondence should be addressed.
Presented at the 37th International Symposium on Dynamical Properties of Solids (DyProSo 2019), Ferrara, Italy, 8–12 September 2019.
Proceedings 2019, 26(1), 31; https://doi.org/10.3390/proceedings2019026031
Published: 5 September 2019
(This article belongs to the Proceedings of The 37th International Symposium on Dynamical Properties of Solids)
Bi2Fe4O9 is a common by-product in the synthesis of the multiferroic compound BiFeO3 and has been claimed itself to display multiferroic properties [1]. The lattice formed by the two different sites of four iron Fe3+ magnetic atoms is quite remarkable as it materializes the first analogue of a magnetic pentagonal lattice [2]. For its peculiar lattice geometry it has attracted interest in the field of geometrical frustration. At room temperature and atmospheric pressure, the crystal structure is orthorhombic within the Pbam space-group and the compounds undergoes a magnetic phase transition at 238 K from a paramagnetic state toward a non collinear magnetic state characterized by a propagation vector k = (1/2, 1/2, 1/2) and a large degree of frustration (θp/TN ~ 7) [2]. Recently it has been shown that Bi2Fe4O9 undergoes a structural transition under pressure at 6–8 GPa toward the maximal non-isomorphic subgroup Pbnm, with c’ = 2c. The driving force of the phase transition is the displacement of the O1 oxygen atom from fully constrained Wyckoff position 2b to a less-constrained 4c one [3]. Previous studies have reported the investigation of dynamical properties by mean of Raman spectroscopy both at ambient condition and at high pressure in a diamond anvil cell [3,4]. However, the vibrational modes involving O1 oxygen atoms are not Raman active but infrared active.
We will report the first polarized infrared spectroscopy measurement of Bi2Fe4O9 performed in a DAC from 1 to 20 GPa in the far-infrared range [60–800 cm−1] and at low temperature. The measurements have been performed at the AILES beamline of synchrotron SOLEIL exploiting the high-pressure/low-temperature set-up [5] coupled with the high brilliance of the radiation source in a wide spectral range on a very thin sample (~50 µm) placed between diamonds with culets of 500 µm diameter. From our high quality spectra, we are able to identify the B3u and B2u modes within the (ab)-plane. Interestingly, while all phonon frequencies increase with pressure, the phonon mode around 200 cm−1 undergoes an anomalous softening with increasing pressure. In order to assign the phonon modes and reveal the microscopic mechanism of the high-pressure transition we also have performed DFT calculation at different pressures. The calculation mostly accounts for the measured phonon modes allowing the assignation of atomic motions.

References

  1. Singh, A.K.; Kaushik, S.D.; Kumar, B.; Mishra, P.K.; Venimadhav, A.; Siruguri, V.; Patnaik, S. Substantial magnetoelectric coupling near room temperature in Bi2Fe4O9. Appl. Phys. Lett. 2008, 92, 132910. [Google Scholar] [CrossRef]
  2. Ressouche, E.; Simonet, V.; Canals, B.; Gospodinov, M.; Skumryev, V. Magnetic frustration in an iron-based cairo pentagonal lattice. Phys. Rev. Lett. 2009, 103, 267204. [Google Scholar] [CrossRef] [PubMed]
  3. Friedrich, A.; Biehler, J.; Morgenroth, W.; Wiehl, L.; Winkler, B.; Hanfland, M.; Tolkiehn, M.; Burianek, M.; Mühlberg, M. High-pressure phase transition of Bi2Fe4O9. J. Phys. Condensed Matter 2012, 24, 145401. [Google Scholar] [CrossRef] [PubMed]
  4. Iliev, M.N.; Litvinchuk, A.P.; Hadjiev, V.G.; Gospodinov, M.M.; Skumryev, V.; Ressouche, E. Phonon and magnon scattering of antiferromagnetic Bi2Fe4O9. Phys. Rev. B 2010, 81, 024302. [Google Scholar] [CrossRef]
  5. Voute, A.; Deutsch, M.; Kalinko, A.; Alabarse, F.; Brubach, J.-B.; Capitani, F.; Chapuis, M.; Phuoc, V.T.; Sopracase, R.; Roy, P. New high-pressure/low-temperature set-up available at the AILES beamline. Vib. Spectroscopy 2016, 86, 17. [Google Scholar] [CrossRef]

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MDPI and ACS Style

Verseils, M.; Beauvois, K.; Litvinchuk, A.; deBrion, S.; Simonet, V.; Ressouche, E.; Skumryev, V.; Gospodinov, M. Investigation of High Pressure Phase Transition by Means of Infrared Spectroscopy in the Cairo Frustrated Pentagonal Magnet Bi2Fe4O9. Proceedings 2019, 26, 31. https://doi.org/10.3390/proceedings2019026031

AMA Style

Verseils M, Beauvois K, Litvinchuk A, deBrion S, Simonet V, Ressouche E, Skumryev V, Gospodinov M. Investigation of High Pressure Phase Transition by Means of Infrared Spectroscopy in the Cairo Frustrated Pentagonal Magnet Bi2Fe4O9. Proceedings. 2019; 26(1):31. https://doi.org/10.3390/proceedings2019026031

Chicago/Turabian Style

Verseils, M., K. Beauvois, A. Litvinchuk, S. deBrion, V. Simonet, E. Ressouche, V. Skumryev, and M. Gospodinov. 2019. "Investigation of High Pressure Phase Transition by Means of Infrared Spectroscopy in the Cairo Frustrated Pentagonal Magnet Bi2Fe4O9" Proceedings 26, no. 1: 31. https://doi.org/10.3390/proceedings2019026031

APA Style

Verseils, M., Beauvois, K., Litvinchuk, A., deBrion, S., Simonet, V., Ressouche, E., Skumryev, V., & Gospodinov, M. (2019). Investigation of High Pressure Phase Transition by Means of Infrared Spectroscopy in the Cairo Frustrated Pentagonal Magnet Bi2Fe4O9. Proceedings, 26(1), 31. https://doi.org/10.3390/proceedings2019026031

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