Magnetic phases evolution in the LaMn1-xFexO3 y system - Condensed Matter > Strongly Correlated ElectronsReport as inadecuate




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Abstract: We have investigated the crystal structure and magnetic properties forpolycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0,prepared by solid state reaction in air. All samples show the ORT-2orthorhombic structure that suppresses the Jahn-Teller distortion, thusfavoring a ferromagnetic FM superexchange SE interaction betweenMn^{3+}-O-Mn^{3+}. For x=0.0 the oxygen excess y ~ 0.09 produces vacancies inthe La and Mn sites and generates a fraction around 18% of Mn^{4+} ions and 82%of the usual Mn^{3+} ions, with possible double exchange interaction betweenthem. The Fe doping in this system is known to produce only stable Fe^{3+}ions. We find an evolution from a fairly strong FM phase with a Curietemperature T {C} ~ 160 K, for x=0.0, to an antiferromagnetic AFM phase withT {N} = 790 K, for x=1.0, accompanied by clear signatures of a cluster-glassbehavior. For intermediate Fe contents a mixed-phase state occurs, with agradual decrease increase of the FM AFM phase, accompanied by a systematictransition broadening for 0.2 < x < 0.7. A model based on the expected exchangeinteraction among the various magnetic-ion types, accounts very well for thesaturation-magnetization dependence on Fe doping.



Author: O. F. de Lima 1, J. A. H. Coaquira 2, R. L. de Almeida 3, L. B. de Carvalho 3, S. K. Malik 3 1Instituto de Fisica, UNICAMP, Campi

Source: https://arxiv.org/







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