Enhancement of magnetoresistance with the variation of particle size in La0.68−xYxCa0.32MnO3, x = 0.0, 0.4, 0.5, 0.6

Abstract

Huge magnetoresistance (MR) has been achieved in La0.68Ca0.32MnO3, by optimal substitution. To explore the origin of this giant enhancement of MR, we have carried out magnetic and magneto transport measurements of La0.68−xYxCa0.32MnO3, x = 0.0, 0.4, 0.5, 0.6 compounds in detail. Our analysis indicates that the disorder introduced by yttrium substitution plays the crucial role in the magneto resistive properties in this series. A large MR has been observed in optimally doped x = 0.5. In this compound, an MR value as high as 1.5 × 107% at a temperature of 50 K has been achieved for an external magnetic field of 90 kOe. The extraordinarily enhanced and large MR value has been described using a phenomenological model of percolation via ferromagnetic clusters. At the specific temperature sizes of these s compounds increases and MR% is likewise increased. For x = 0.6,not enough to create the percolation path.