A-site substitution effects on the magnetic and transport properties in La1.4−zYzSr1.6−yBayMn2O7

The magnetic and transport properties of bilayer manganites La1.4−zYzSr1.6−yBayMn2O7 (z = 0, 0.05; y = 0, 0.05) have been investigated. Doping reduces the magnetization and conductance, and shifts magnetic transition temperature and insulator-metal transition temperature to lower temperature. Different changes of magnetic and transport behaviors among Y doping (y = 0; z = 0.05), Ba doping (y = 0.05; z = 0) and Y and Ba co-doping (y = z = 0.05) are observed. These results can be explained by considering A-site ionic size mismatch, the orbital character of eg electrons, and the Y and Ba preferential occupancy.