Effect of Cr-doping on the magnetic and electrical properties of La0.4Ca0.6MnO3

The magnetic and electrical properties of electron-doped manganite La(0.4)Ca(0.6)Mn(1-y)Cr(y)O(3) polycrystalline samples (y=0.02, 0.04, and 0.06) prepared by a sol-gel technique have been investigated between 5 and 325 K in magnetic fields ranging from 0 to 5 T. Both the M-T and M-H data indicate that these Cr-doped manganites exhibit multiple ferromagnetic phases in which the relative amounts of each phase and temperatures of their appearance change with Cr content. The temperature dependence of the zero-field resistivity indicates that a transition occurs below 150 K from an insulating (semiconducting) behavior to a behavior exhibiting a temperature-independent plateau with the magnitude of a semimetal. In addition a large field-induced behavior is found in both the magnetoresistance and magnetization at temperatures correlated to the ferromagnetic semimetallic phase being induced, which results in a large magnetoresistance at the lowest temperatures. (c) 2008 American Institute of Physics.