The effect of transition element doping on the electronic and magnetic properties of La1.4Sr1.6Mn2O7

The effect of transition element (TE=Cr, Fe, Co, Ni, Cu, Zn) doping on the electronic transport and magnetic properties in the bilayer manganite La1.4Sr1.6Mn2O7 is studied for the same dopant concentration fixed at 2%. Doping does not cause change in structure but different behavior in magnetic and transport properties. Except for Cr, all the other dopings significantly shift the magnetic transition temperature (TC) to a lower temperature. Associated with such a decrease, the insulator–metal transition temperature (TIM) decreases and the peak resistivity (ρpρp) at TIM increases. Cr doping enhances TC and TIM as well as decreases ρpρp. Fe doping apparently has a stronger effect than Co and Ni doping. It is also indicated that Cu doping causes an anomalously large increase in ρpρp. These behaviors are compared with those observed in other bilayer manganites such as La1.2Sr1.8Mn2O7 as well as in La0.7Ca0.3Mn1−xTExO3.