Magnetic, electric and thermoelectric behavior of electron-doped La _1-xSb_xMnO₃ (x = 0.05, 0.10 and 0.15) manganites

A systematic investigation of magnetic, electric and thermoelectric properties of sol-gel prepared electron-doped La_1-xSb _xMnO₃ (x = 0.05, 0.10 and 0.15) was undertaken to understand the magnetotransport behavior. The X-ray diffraction and X-ray photoelectron spectroscopy measurements confirm that the samples with x = 0.05 and 0.10 are having single phase, while x = 0.15 shows a secondary phase. The second phase observed in the sample is found to have considerable influence on the magnetic and electrical transport behavior. The magnetic and electrical transport properties in low temperature ferromagnetic region may be explained in terms of spin waves and phonons, while in the paramagnetic region the adiabatic small polaron model is invoked. These materials are found to exhibit magnetoresistance values ranging from 30% to 40% and 55% to 65% at 3 and 7 T magnetic fields respectively.