Abstract
New complex magnetic frustrated materials La2-xErxTi2O7 (0 <= x <= 0.075) have been synthesized by solid-solid method. The crystallographic and magnetic properties were studied as a function of substitution of the La3+ ion by the Er3+ one. All samples are found to be single phase and crystallize in the monoclinic structure with P-21 space group. Magnetic measurements have revealed the presence of dominant antiferromagnetic interactions and the absence of magnetic ordering until a temperature of 2 K. The magnetic study suggests that the Curie-Weiss temperature (theta(CW)) is negative, as expected in the frustrated lanthanide sublattice in the Ln(2-x)Ln'xM2O7 structure. From the frustration index integral = theta CW/T-N, we have deduced the presence of a strong frustration phenomenon. The critical properties of the antiferromagnetic behavior, for x = 0.025, 0.05 and 0.075 samples, have been investigated. It was found that the 2D-self-avoiding walk (SAW) model is the best one to describe the critical phenomena.