Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10710064 | Journal of Magnetism and Magnetic Materials | 2012 | 8 Pages |
Abstract
(La0.6Eu0.4)0.67Ca0.33MnO3 has been prepared in the shape of nanoplates of single crystallites (an orthorhombic structure) through polymer templates. HRTEM images reveal 18, 25, and 30Â nm thicknesses of plates after heating a precursor powder at 873, 1073, and 1273Â K in air for 2Â h. These values present average crystallite size determined from broadening of the X-ray diffraction peaks. A spin-glass-like surface (GS) overlayer (3-5Â nm thickness) in such plates facilitates a ferromagneticâferrimagnetic reordering with markedly suppressed Curie point TC, i.e., as small as 90Â K in a 873Â K heated sample, from the parent value 268Â K. The TC point increases to 103Â K (or 120Â K) when heating at higher temperature 1073 (or 1273Â K), during which the core grows at the expense of the overlayer. The GS tailors as high coercivity Hc as 617Â Oe in the zero field cooled (ZFC) sample that is decreased to 500Â Oe in the field cooled (FC) sample in the surface spin-freezing along the field direction. The Hc-value (ZFC) that steps down successively to 252Â Oe on the overlayer is thinned down by heating at 1273Â K. Samples heated at 873, 1073, or 1273Â K have regularly increased saturation magnetization 35.3, 63.9, or 69.6Â emu/g in ZFC, while 43.7, 70.2, or 75.5Â emu/g in FC measured at 10Â K. The ferrimagnetic reordering are described based on the scenario of an antiferromagnetic exchange coupling between the Eu3+ and Mn3+ (or Mn4+) sublattices.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Debasis De, Shanker Ram, Alok Banerjee, Sanat K. Roy,