Reference : ac magnetic behavior of large-grain magnetoresistive La0.78Ca0.22Mn0.90Ox materials
Scientific journals : Article
Engineering, computing & technology : Materials science & engineering
Physical, chemical, mathematical & earth Sciences : Physics
ac magnetic behavior of large-grain magnetoresistive La0.78Ca0.22Mn0.90Ox materials
Vanderbemden, Philippe mailto [Université de Liège - ULiège > > Capteurs et systèmes de mesures électriques >]
Vertruyen, Bénédicte mailto [Université de Liège - ULiège > > Chimie inorganique structurale >]
Rulmont, André mailto [Université de Liège - ULiège > > Chimie inorganique structurale >]
Cloots, Rudi mailto [Université de Liège - ULiège > > Chimie inorganique structurale >]
Dhalenne, Guy [> > > >]
Ausloos, Marcel mailto [Université de Liège - ULiège > Département de physique > Physique statistique appliquée et des matériaux >]
Physical Review. B
American Physical Society
Yes (verified by ORBi)
College Pk
[en] We report a detailed set of ac magnetic measurements carried out on bulk large grain La-Ca-Mn-O samples extracted from a floating zone method-grown rod. Three samples with La0.78Ca0.22Mn0.90Ox stoichiometry but differing in their microstructure were investigated by electrical resistivity and ac susceptibility measurements: (i) a single grain sample, (ii) a sample containing two grains, and (iii) a polycrystalline sample. We show that the superimposition of dc magnetic fields during ac magnetic susceptibility measurements is an efficient way for characterizing the magnetic transition of samples with different microstructures. Whereas both single grain and polycrystalline samples display a single susceptibility peak, an additional kink structure is observed in the case of the double grain sample. The temperature dependence of the ac susceptibility measured with superimposed dc magnetic fields is analyzed in the framework of second-order phase transition ideas. The relations between the critical exponents (beta+gamma ~ 1.5, delta ~ 2.5) are found to be close to those of the mean-field model for all samples. This is attributed to the disordering caused by unoccupied Mn sites. ©2003 The American Physical Society.
Services Universitaires Pour la Recherche et les Applications Technologiques de Matériaux Électro-Céramiques, Composites, Supraconducteurs - SUPRATECS
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS
Researchers ; Professionals

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