Magnetic properties of a ferromagnetic double spin chain compound LaCrOS2

Magnetic properties of LaCrOS2, in which Cr ions form zigzag chains, well separated with each other, have been studied. Because the temperature dependence of the inverse magnetic susceptibility above 200 K obeys Curie–Weiss law, we obtain a Weiss temperature Θp of 75 K. The large positive Weiss temperature and the steep increase of the magnetization below 80 K show that ferromagnetic interaction between Cr ions is dominant in this compound. The magnetization curves, however, show no spontaneous magnetization down to 4.2 K. This indicates that Cr ions do not order three dimensionally at least above 4.2 K. The saturation magnetization at 4.2 K is about 2.5μB per Cr ion. In the low temperature range, the differential magnetic susceptibility χd is expressed approximately as χd=(C/T)exp Δ/(kBT), where Δ is equal to 131 K. The temperature dependence of χd at low temperature suggests that a zigzag chain of Cr spins in this compound behave like a one-dimensional ferromagnetic Ising chain which has an excitation g...