Magnetic Properties of La0.45Sr0.55Mn0.95Co0.05O3

The magnetic properties of polycrystalline La0.45Sr0.55Mn0.95Co0.05O3 were investigated in this work. With the doping of Co ions in La0.45Sr0.55MnO3, the ferromagnetism is enhanced with the Curie temperature, T-C, increasing from 290 to 317 K; on the other hand, the antiferromagnetism is nearly destroyed in the low-temperature region. The temperature dependence of the inverse magnetic susceptibility, chi(-1)(T), follows the Curie-Weiss law in the high-temperature region. With decreasing temperature, the chi(-1)(T) curve deviates from the Curie-Weiss linear behavior at temperatures above T-C, showing a sharp downturn. This reflects the characteristic of a Griffiths singularity. In the temperature region between 65 and 181 K, the Bloch T-3/2 law is found to dominate the temperature dependence of the magnetization. At temperatures below 65 K, the deviation from the T-3/2 law reveals that a residual antiferromagnetic component still exists in the low-temperature region. We also investigated the relationship between the magnetization and the applied field, M(H). M(H) at 5 K further confirms the enhanced ferromagnetism with a slight antiferromagnetic component in the compound. The M(H) at 350 K further supports the existence of a Griffiths phase