SCHEDULED MAINTENANCE
Ferromagnetism and magnetoresistance in monolayered manganites Ca2–xLnxMnO4
Abstract
Ferromagnetism (T
c
) and negative magnetoresistive properties (maximum at 30 K) are observed in the monolayered manganites Ca
2–x
Ln
x
MnO
4
(Ln=Pr, Sm, Gd, Ho and 0<x7≤0.20) despite their pure bidimensional character. A detailed structural study was carried out using X-ray diffraction, electron diffraction, and high resolution electron microscopy. This shows that they exhibit an orthorhombic cell, with a≊b≊ap2, c≊√12 Å and Aba2 or Abma as possible space groups. In all these oxides, (001)-type twinning is observed, on a unit cell scale, creating in this way a local periodicity of 24 Å. In the x=0.08 doped samples, it is observed that the microstructural state is strongly dependant on the synthesis process but it does not affect the magnetotransport properties.
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