Anomalous temperature dependence of the magnetization in La0.84Sr0.16MnO3

The superconducting quantum interference device (SQUID) magnetization measurements have been performed on single crystal manganites La1−xSrxMnO3 (x=0.16;0.17) previously studied by the NMR method. For the x=0.16 sample an anomaly in the temperature dependence of the saturation magnetization at T1≈130 K is observed, which manifests itself as a cusp in dm/dT. This temperature lying well below the metal-insulator transition at TMI=157 K seems to correspond to an orbital ordering temperature Too indicated also by the decrease in the low field FC susceptibility. The observed anomaly, which is also reproduced in the temperature dependence of the NMR frequency, is ascribed to a continual decrease in the exchange interaction within the temperature interval 60 K and the difference between TMI and Too to an inherent inhomogeneity in Sr concentration. The relative SQUID magnetizations are compared with the NMR values.