Strain-Induced Insulator State and Giant Gauge Factor of La 0.7 Sr 0.3 CoO 3 Films

摘要: A strain-induced change of the electrical conductivity by several orders magnitude has been observed for ferromagnetic ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{CoO}}_{3}$ films. Tensile strain is found to drive narrow-band metal highly insulating. Reversible applied using a piezoelectric substrate reveals huge resistance modulations including giant piezoresistive gauge factor 7000 at 300 K. Magnetization data recorded statically and reversibly strained films show moderate changes. This indicates rather weak response low-temperature Co spin state. We suggest that static Jahn-Teller--type deformation ${\mathrm{CoO}}_{6}$ units may provide localization mechanism also impact on electronic transport in paramagnetic regime.