Magnetic study of the mixed orthotitanate La1−xSmxTiO3 (0≦x≦1)

Abstract

Magnetic and structural properties were investigated for the mixed lanthanide solid solution La1−xSmxTiO3 (x=0, 0.0625, 0.125, 0.1875, 0.25, 0.375, 0.5, 0.75 and 1). It was found that all the systems form an orthorhombic perovskite phase (GdFeO3 type) throughout the whole composition range 0≦x≦1. LaTiO3 (x=0) showed so-called canted-antiferromagnetic ordering at TN (Neel temperature) ∼130 K. The ordering temperature of SmTiO3 (x=1) was ∼50 K. The solid solution compounds exhibited magnetic ordering at TN as well, which decreases steadily with x. However, the χ−T (d.c. susceptibility–temperature) curves in some La-rich systems with 0<x<0.3, where crystallographic modification from LaTiO3 is rather minor, were entirely different from those of the end compounds, and represented characteristic susceptibility peaks below TN values. Around the susceptibility peak temperatures (TP values), the most pronounced magnetic hysteresis loops were obtained in the magnetization–field (M–H) isotherm curves. At lower temperatures, magnetization (M) was found to show time (t)-dependent relaxation behavior as observed in spin-glass and/or cluster-glass systems. From the absence of the two characteristic features of spin-glass, i.e., aging effect below Tg (spin-glass transition temperature) and negative divergence of nonlinear AC susceptibilities at Tg, the onset of a cluster-glass state is suggested in these La-rich systems.