Effect of bias current on the resisitivity and photoconductivity of oxygen-deficient La_(2/3)Sr_(1/3)MnO_(3-δ) thin films

摘要

The influence of bias current on resistivity and photoconductivity in oxygen-deficient La_(2/3)Sr_(1/3)MnO_(3-δ) thin films has been investigated. There exists a giant resistance drop induced by dc electrical currents alone especially near the temperature of resistance peak (T_p). Moreover, the photoconductivity emerges only when the current exceeds a threshold and this effect is quite different from magnetoresistance induced by magnetic fields. It is found that the magnitude of photoconductivity increases with increasing of bias current and the threshold current increases with decreasing temperatures and increasing magnetic fields. The magnitude of photoconductivity achieves 10.2% at temperature of 100 K with light density of 4.3 mW/cm~2 and current of 1 mA. The current-assisted electroresistance and photoconductivity are discussed based on the delocalization of localized state by light illumination and bias current.