Disorder effect on the magnetic behavior of mechanically alloyed Fe1-x Alx (0.2≤x≤0.4)
We report on the magnetic properties of Fe1-x Alx alloys (0.2≤x≤0.4) produced by mechanical alloying by milling pure element powders for t=12, 24, and 36 h. The alloys present a bcc lattice with compositional disorder and are ferromagnetic at room temperature, independently of the milling time. The...
| Autores: | , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2009 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/100722 |
| Acceso en línea: | http://hdl.handle.net/10261/100722 |
| Access Level: | acceso abierto |
| Palabra clave: | Superparamagnetism Spin glasses Mossbauer effect Mechanical alloying Magnetic susceptibility Aluminium alloys Antiferromagnetism Crystal structures Ferromagnetism Freezing Iron alloys Lattice constants Localised modes Magnetic hysteresis |
| Sumario: | We report on the magnetic properties of Fe1-x Alx alloys (0.2≤x≤0.4) produced by mechanical alloying by milling pure element powders for t=12, 24, and 36 h. The alloys present a bcc lattice with compositional disorder and are ferromagnetic at room temperature, independently of the milling time. The lattice parameter of the x=0.2 sample presents a small decrease with t, whereas those of the x=0.3 and 0.4 samples remain constant independently of the milling time. The magnetic properties of the alloys with x=0.2 and 0.3 do not show important variations with t, while those of x=0.4 are strongly dependent on the milling time. For this latter alloy it was found that: (i) despite being the most diluted of the series, it presents a well developed ferromagnetic order at room temperature as the Mössbauer and hysteretic data have shown; (ii) the temperature dependence of the ac susceptibility and the Mössbauer spectra recorded at different temperatures evidence the occurrence of reentrant spin-glass and superparamagnetic phenomena. The enhancement of the ferromagnetic behavior and the presence of reentrant spin-glass freezing temperature and of a superparamagnetic blocking process are interpreted in terms of a simple localized model based on the disorder present in that alloy and on the occurrence of competitive interactions, namely, the ferromagnetic nearest-neighbor Fe-Fe interactions and the antiferromagnetic near-nearest-neighbor Fe-Fe ones. Taken together, these results evidence that the stabilization of the magnetic order takes place in the x=0.4 sample exclusively through the induction of compositional disorder and without any contribution from the lattice expansion. © 2009 The American Physical Society. |
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