Room temperature giant magnetoresistance in La_1-xPb_xMnO₃

Oxides of the La_1-xPb_xMnO₃ system show giant magnetoresistance around 300 K. In La_1-xPb_xMnO₃ the magnitude of the magnetoresistance (MR) at 320 K is 85% at 6 T and it is nearly temperature independent over a temperature range 40-320 K. All the compositions (0.1<or=x<or=0.5) show a peak in resistivity around 300-340 K and the magnitude of the MR also shows a peak around the same temperatures. This investigation suggests how to hole dope LaMnO₃ in order to achieve maximum MR around 300 K so that these materials can have practical applications.