Evidence of magnetic dipolar interaction in micrometric powders of the Fe50Mn10Al40 system: Melted alloys

• Published in: Journal of magnetism and magnetic materials 2013-02, Vol.327, p.137-145
• Main Authors: Pérez Alcázar, G.A., Zamora, L.E., Tabares, J.A., Piamba, J.F., González, J.M., Greneche, J.M., Martinez, A., Romero, J.J., Marco, J.F.
• Format: Article
• Language: English
• Subjects: 57Fe Mössbauer spectrometry; Alloys; Condensed Matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diamagnetism, paramagnetism and superparamagnetism; Exact sciences and technology; Ferromagnetism; Fe–Mn–Al alloy; Freezing; Henkel plot; Iron; Magnetic moment; Magnetic properties and materials; Magnetic property; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Magnetism; Mössbauer effect; other γ-ray spectroscopy; Origins; Particle size; Physics; Small particles and nanoscale materials; Studies of specific magnetic materials; X-ray diffraction
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2012.09.035

Powders of melted disordered Fe50Mn10Al40 alloy were separated at different mean particle sizes as well as magnetically and structurally characterized. All the samples are BCC and show the same nanostructure. Particles larger than 250μm showed a lamellar shape compared to smaller particles, which exhibited a more regular form. All the samples are ferromagnetic at room temperature and showed reentrant spin-glass (RSG) and superparamagnetic (SP)-like behaviors between 30 and 60K and 265 and > 280K, respectively, as a function of frequency and particle size. The freezing temperature increases with increasing particle size while the blocking one decreases with particle size. The origin of these magnetic phenomena relies in the internal disordered character of samples and the competitive interaction of Fe and Mn atoms. The increase of their critical freezing temperature with increasing mean particle size is due to the increase of the magnetic dipolar interaction between the magnetic moment of each particle with the field produced by the other magnetic moments of their surrounding particles. ► The effect of particle size in microsized powders of Fe50Mn10Al40 melted disordered alloy is studied. ► Dipolar magnetic interaction between particles exists and this changes with the particle size. ► For all the particle sizes the reentrant spin- glass and the superparamagnetic-like phases exist. ► RSG and SP critical temperatures increase with increasing the dipolar magnetic interaction (the mean particle size).