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Memorias de investigación
Research Publications in journals:
: Dynamics of AC susceptibility and coercivity behaviour in nanocrystalline TbAl1.5Fe0.5 alloys
Year:2013
Research Areas
  • Magnetism
Information
Abstract
The static and dynamic magnetic macroscopic properties of bulk and nanocrystalline TbAl1:5Fe0:5 alloys have been investigated. In bulk state, this alloy is understood as a reentrant ferromagnet. This is characterized by a ferromagnetic Curie transition at 114 K, as deduced from magnetization including Arrott plots, higher than that of TbAl2. The reentrance is found at lower temperatures, below 54 K, with a cluster glass behavior setting in, deduced from the magnetization irreversibility. This is accompanied by an abrupt increase of the coercivity from 0.08 kOe to 15 kOe at 5 K, respect to the TbAl2 alloy. Room temperature M¿ossbauer spectroscopy confirms the paramagnetic state of such a bulk alloy. The spin dynamics within the disordered magnetic state is described by the AC-susceptibility which shows a Vogel-Fulcher law for the slowing down process. This is caused by a random anisotropy affecting the existing clusters. The production of milled TbAl1:5Fe0:5 alloys enhances the presence of magnetic disorder and results in the particle downsizing toward the nanocrystalline state (close to 10 nm). In this case, two frequency-dependent contributions exist, with different activation energies, one of them can not be described by ideal spin glass nor blocking/unblocking (nanoparticle) processes. In addition, the coercivity reduces to 1 kOe with the decrease of the size as a consequence of the existence of single domain particles. The results are explained by the intricate interplay between exchange interactions and magnetocrystalline anisotropy with disorder and size effects.
International
Si
JCR
Si
Title
Journal of Magnetism And Magnetic Materials
ISBN
0304-8853
Impact factor JCR
1,826
Impact info
Volume
326
10.1016/j.jmmm.2012.08.050
Journal number
326
From page
58
To page
65
Month
ENERO
Ranking
Participants
  • Autor: Daniel Rojas Pupo (UPM)
Research Group, Departaments and Institutes related
  • Creador: Departamento: Física e Instalaciones Aplicadas a la Edificación, al Medio Ambiente y al Urbanismo
S2i 2020 Observatorio de investigación @ UPM con la colaboración del Consejo Social UPM
Cofinanciación del MINECO en el marco del Programa INNCIDE 2011 (OTR-2011-0236)
Cofinanciación del MINECO en el marco del Programa INNPACTO (IPT-020000-2010-22)