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Title: A 57Fe Mossbauer study of charge ordering and phase separation in the rare-earth manganates, Nd0.5Ca0.5MnO3 and Nd0.5Sr0.5MnO3
Authors: Vanitha, P V
Nagarajan, R
Rao, C N R
Keywords: rare-earth manganates
charge ordering
magnetic disorder
Fe-57 Mossbauer spectroscopy
phase separation
Issue Date: Aug-2003
Publisher: Academic Press Inc Elsevier Science
Citation: Journal of Solid State Chemistry 174(1), 74-79 (2003)
Abstract: Mössbauer studies of 2% 57Fe-doped Nd0.5Ca0.5MnO3 and Nd0.5Sr0.5MnO3 have been carried out over the 4.2–300 K range after ensuring that such doping does not change their basic properties. The charge-ordering transition in these manganates is marked by abrupt changes in the quadrupole splitting. In the case of Nd0.5Ca0.5MnO3, two phases manifest themselves on cooling below the charge-ordering transition temperature. The evolution of the spectra as a function of temperature shows that long-range magnetic order does not occur sharply. The observed evolution with temperature is different in the two materials studied. In Nd0.5Ca0.5Mn0.9857Fe0.02O3, it resembles that of a disordered magnetic material, whereas the temperature dependence of line shape of Nd0.5Sr0.5Mn0.9857Fe0.02O3 is typical of a superparamagnetically relaxed magnetic system. Although both the manganates show well-resolved magnetic hyperfine spectra at 4.2 K, the lines are slightly broad indicating possible coexistence of phases at low temperatures. A weak paramagnetic signal is also seen in the spectra of both the manganates at 4.2 K.
Description: Restricted Access
Other Identifiers: 0022-4596
Appears in Collections:Research Papers (Prof. C.N.R. Rao)

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