DEPENDENCE OF THE MAGNETIC-PROPERTIES GD2-XCEXCUO4, 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.15, ON THEIR PARTICLE-SIZE

Gd2-xCexCuO4, 0 less-than-or-equal-to x less-than-or-equal-to 0.15, have been synthesized by the solid state reaction, the sol-gel technique and the water-in-oil microemulsion, in order to vary the particle size. The samples have been characterized by x-ray diffraction, photon correlation spectroscopy and transmission electron microscopy. Magnetization and ac susceptibility measurements were performed between 4 and 300 K. The extrapolated linear part of the inverse magnetization shifts to lower temperatures as the particle size decreases. The internal field associated to the WF of the Cu moments diminishes with the particle diameter. Differences between the zero-field-cooling and the field-cooling magnetization curves were observed for T < T(N). These differences depend on the particle size.