Neutron diffraction, ac magnetic susceptibility, and dc electric resistivity measurements were performed to study the structural, magnetic, and electric properties of naturally bilayered La2-2xSr1+2xMn2O7, with x = 0.3, 0.4, and 0.5. The ordering temperature of the Mn spins shifted to a higher temperature as the doping concentration was increased. Both ferromagnetic and antiferromagnetic correlations were evident. The predominant interaction in the x = 0.3 and 0.4 compounds was ferromagnetic, whereas it was antiferromagnetic in the x = 0.5 compound. Both the in-phase and out-of-phase susceptibilities showed complex patterns, indicating that the systems were magnetically very active. An external field as weak as 100 Oe strongly altered the susceptibility patterns. Magnetic fluctuations were evident at all temperatures studied. A structural change, which we believe to be induced by the charge ordering, occurred at around 220 K.
|Number of pages||11|
|Journal||Chinese Journal of Physics|
|State||Published - 2001|