Large Piezoresistance and Pressure-Induced Change in Electric Properties in Perovskite-like La_0.85Sr_0.15MnO₃

Uniaxial pressure dependencies of the electric properties of perovskite-like La_l-xSr_xMnO₃(0.2 ≤x ≤0.6) system have been investigated. A large nonlinear piezoresistance effect and a remarkable pressure-induced change of metal-semiconductor (M-S) transition have been observed. For La_0.7Sr_0.3MnO₃, the piezoresistance value can reach about 86% at 290K under a pressure of 16.8MPa, and the pressure coefficient of T_p, the onset of the M-S transition, is as high as 6.4 K/MPa, which is significantly larger than that of known similar pressure effects. These pressure effects suggest that the resistivity of the perovskite compounds is relative not only to double exchange but also to the symmetry of lattice. This phenomenon may provide another route in understanding the colossal magnetoresistance behavior in the perovskites.