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Type: Artigo de periódico
Title: Extrinsic And Intrinsic Features Above Tc In Layered Manganite: La1.2sr1.8mn2o7
Author: Moreno N.O.
Pagliuso P.G.
Rettori C.
Gardner J.S.
Sarrao J.L.
Thompson J.D.
Huber D.L.
Garcia-Flores A.
Oseroff S.B.
Abstract: We have performed EPR and DC magnetization measurements on single crystals of La1.2Sr1.8Mn2O7. Similar to previous authors, we found an increase in the magnetization, M, near 300 K, a temperature well above TC approx. 125 K. Previously, this high temperature (approx. 300 K) feature has been suggested to be intrinsic to the system. We have observed at these high temperatures the appearance of new ferromagnetic resonances, FMR. Within the experimental error the volume of sample required to explain the extra M and the intensity of the FMR is the same. We conclude that the increase in M and the FMR are due to the presence of extrinsic Ruddlesden-Popper (RP) phases and not to intrinsic effects as has been claimed. Furthermore, the resonance field of the EPR line due to the La1.2Sr1.8Mn2O7 phase presents a measurable temperature-dependent anisotropy up to approx. 450 K. The anisotropy is proportional to M, independent of the extrinsic RP phase content, and intrinsic to the system. We show that demagnetization effects can explain only part of the anisotropy. The role of short-range magnetic ordering in the observed intrinsic features cannot be disregarded, however.
Editor: Elsevier Science Publishers B.V., Amsterdam, Netherlands
Rights: fechado
Identifier DOI: 10.1016/S0921-4526(00)00496-8
Date Issue: 2000
Appears in Collections:Unicamp - Artigos e Outros Documentos

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