Abstract :
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 ( ρ p ) at TIM increases. Cr doping enhances TC and TIM as well as decreases ρ p . 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 ρ p . These behaviors are compared with those observed in other bilayer manganites such as La1.2Sr1.8Mn2O7 as well as in La0.7Ca0.3Mn1−xTExO3.
