Studies on magnetic properties of La0.95Sr0.05CrO3and La0.85Sr0.15CrO3by means of powder neutron diffraction

The magnetic properties of the perovskite-type compounds La1-xSrxCrO3 (x = 0.05 and 0.15) have been investigated. In the magnetic susceptibility measurements, three magnetic anomalies have been observed for La0.95Sr0.05CrO3 (at 21 K, 85 K and 280 K) and for La0.85Sr0.15CrO3 (at 26 K, 160 K and 267 K). Powder neutron diffraction measurements on these two compounds indicate that the anomaly found at ≈20 K in their susceptibility-temperature curves is not ascribable to the magnetic transition. Heat capacity measurements also show that two anomalies have been found at 90 K and 280 K for La0.95Sr0.05CrO3 and at 160 K, 190 K and 266 K for La0.85Sr0.15CrO3, and no anomaly has been found at ≈20 K. The magnetic structures for all the compounds have been determined to be of G type, in which Cr atoms are antiferromagnetically coupled with the six neighbouring Cr atoms at all of the temperatures. The magnetic moments of Cr atoms are directed parallel to the z-axis of an orthorhombic unit cell for La0.95Sr0.05CrO3 at 10 K and 50 K and for La0.85Sr0.15CrO3 at 10 K and 50 K; the Gz mode dominates. The Gy mode dominates for La0.95Sr0.05CrO3 at 125 K; i.e., a spin reorientation has occurred between 50 K and 125 K.