Detection of para–antiferromagnetic transition in Bi2Fe4O9 powders by means of microwave absorption measurements

• Published in: Journal of magnetism and magnetic materials Vol. 348; pp. 17 - 21
• Main Authors: Alvarez, G., Contreras, J., Conde-Gallardo, A., Montiel, H., Zamorano, R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2013; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron paramagnetic resonance; Electron paramagnetic resonance and relaxation; Exact sciences and technology; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Magnetic transition; Magnetically ordered materials: other intrinsic properties; Microwave and radio-frequency interactions (excluding resonances); Non-resonant microwave absorption; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other interactions of matter with particles and radiation; Physics; Non-resonant microwave absorption; Electron paramagnetic resonance; Magnetic transition; Microwave absorption; Weak ferromagnetism; Sublattices; Line widths; Bismuth Iron Oxides Mixed; Paramagnetic-antiferromagnetic transitions; Magnetic transitions
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2013.08.014

An electron paramagnetic resonance (EPR) study of Bi2Fe4O9 powders is carried out in X-band (8.8–9.8GHz) and the 200–350K temperature range. For all the temperatures, the EPR spectra show a single broad line attributable to Fe3+ (S=5/2) ions. The onset of the para–antiferromagnetic transition has been determined from the temperature dependence of the parameters deduced from EPR spectra: the peak-to-peak linewidth (ΔHpp) and the resonant field (Hres); a weak ferromagnetism is also observed at low temperature and it is attributed to canting of Fe3+ ion sublattices in the antiferromagnetic matrix. The magnetically modulated microwave absorption spectroscopy (MAMMAS) and the low-field microwave absorption (LFMA) are used to give further information on this material. These techniques give evidence of the magnetic transition, suggesting a weak ferromagnetism at low temperature. •The changes in lineshape of the EPR spectra in Bi2Fe4O9 powders are studied.•The onset of the para–antiferromagnetic transition is detected.•A weak ferromagnetism is also observed in this material.•MAMMAS and LFMA techniques are used to give a further knowledge on the bismuth ferrite.