Magnetic exchange interactions induced by Cr-doping in perovskite manganites

The effect of Cr-doping on the structural, magnetic and transport properties of perovskite manganites La0.8Ca0.2Mn1−xCrxO3 (0≤x≤0.7) has been investigated. The Curie temperature (TC) of the Cr-doped samples is almost unchanged up to 30% of Cr-doping. The Cr-doped samples, however, undergo a transition from the parent metallic state to the insulating state below TC. The dc and ac magnetization data suggest that ferromagnetic clusters induced by double exchange interaction between Cr3+ and Mn3+ ions and antiferromagnetic components driven by Cr3+/Mn4+ and Cr3+/Cr3+ interactions are present in the Cr-doped system, which is supported by comparative studies on magnetic and transport properties of LaMnO3+δ and LaMn0.75Cr0.25O3+δ.