High pressure electrical resistivity behaviour on nano-crystalline vacancy doped perovskite manganites

Abstract

We report here for the first time, the pressure dependence of the electrical resistivity of vacancy-doped nano-crystalline manganites up to 2 GPa at room temperature. The nano-crystalline samples with vacancy doping at La- and Mn-sites, respectively, were synthesized by sol–gel technique and particle size was determined by width in the X-ray diffraction peaks. The pressure dependent electrical resistivity measurements on La-deficient system (La 0.9Mn 0.8Fe 0.2O Δ ) and Mn-deficient system (La 0.86Sr 0.14Mn 0.80Fe 0.16O Δ ) show a similar trend by having a sudden change in the resistivity at 0.3 GPa. Further increase in pressure reduces the resistivity monotonically for La-deficient system up to 1.6 GPa while Mn-deficient system undergoes another sudden change in the resistivity at 0.78 GPa. The behaviour of the vacancy-doped systems were compared with stoichiometric system (La 0.8Sr 0.2Mn 0.8Fe 0.2O 3) which showed a similar phase transition at 0.52 GPa. The cross over of localized-electron to band magnetism could be seen clearly through low temperature Mössbauer measurements.