The perovskite solid solutions of the type La2xSr2−2xCo2xRu2−2xO6 with 0.25 ≤ x ≤ 0.75 have been investigated for their structural, magnetic and transport properties. All the compounds crystallize in double perovskite structure. The magnetization measurements indicate a complex magnetic ground state with strong competition between ferromagnetic and antiferromagnetic interactions. Resistivity of the compounds is in confirmation with hopping conduction behaviour though differences are noted especially for x = 0.4 and 0.6. Most importantly, low field (50Oe) magnetization measurements display negative magnetization during the zero field cooled cycle. X-ray photoelectron spectroscopy measurements indicate presence of Co2+/Co3+ and Ru4+/Ru5+ redox couples in all compositions except x = 0.5. Presence of magnetic ions like Ru4+ and Co3+ gives rise to additional ferromagnetic (Ru-rich) and antiferromagnetic sublattices and also explains the observed negative magnetization.
@article{arxiv.1011.2559,
title = {Structure, Transport and Magnetic properties in La$_{2x}$Sr$_{2-2x}$Co$_{2x}$Ru$_{2-2x}$O$_{6}$},
author = {P. S. R. Murthy and K. R. Priolkar and P. A. Bhobe and A. Das and P. R. Sarode and A. K. Nigam},
journal= {arXiv preprint arXiv:1011.2559},
year = {2015}
}