Magnetotransport and magnetic properties of weak ferromagnetic semiconductors : Ca doped LaCrO3

We report the magnetic and magnetotransport properties of Ca doped La1−xCaxCrO3 (x=0, 0.1, 0.2, and 0.3). Both the magnetic and transport properties are very sensitive to Ca substitution. The Neel temperature TN decreases substantially with increasing calcium doping concentration from 290to160K. A weak ferromagnetic state with large coercive fields of up to 3T is present for the Ca doped LaCrO3. The temperature dependence of the resistivity shows that all the Ca doped compounds are semiconducting and their resistivities decrease with increasing Ca for low doping levels. The resistivity curves show thermally activated behavior and a variable range hopping behavior at high temperatures. The magnetotransport measurements show a negative magnetoresistance. Furthermore, an anomalous peak was observed in the field dependence of magnetoresistance for the LCCO materials.