Piezoresistivity in films of nanocrystalline manganites

Abstract

Rare earth manganites having perovskite structure are susceptible to lattice strain. So far most investigations have been done with hydrostatic pressure or biaxial strain. We have observed that hole doped rare-earth manganites, which are known to display colossal magnetoresistance (CMR) also show change in its resistance under the influence of uniaxial strain. We report the direct measurement of piezoresistive response of La_0.67Ca_0.33MnO₃ (LCMO) and La_0.67Sr_0.33MnO₃ (LSMO) of this manganite family. The measurements were carried out on nanostructured polycrystalline films of LCMO and LSMO grown on oxidized Si(100) substrates. The piezoresistance was measured by bending the Si cantilevers (on which the film is grown) in flexural mode both with compressive and tensile strain. At room temperature the gauge factor ∼10-20 and it increases to a large value near metal-insulator transition temperature (T_P) where the resistivity shows a peak.