Effect of La³⁺ substitution with Gd³⁺ on the resistive switching properties of La_0.7Sr_0.3MnO ₃ thin films

This study demonstrated that the resistive switching voltage of perovskite manganite material could be controlled by A-site cation substitution in "A" MnO₃ perovskite manganite structure. A partial substitution of La³⁺ in La_0.7Sr_0.3MnO ₃ with smaller cation Gd³⁺ induced A-site vacancy of the largest Sr²⁺ cation with surface segregation of SrO_y due to ionic size mismatch, and the induced vacancies reduced migration energy barrier. The operating voltage decreased from 3.5 V to 2.5 V due to a favorable condition for electrochemical migration and redox of oxygen ions. Moreover, surface-segregated SrO_y was enhanced with Gd-substitution and the SrO_y reduced Schottky-like barrier height and resistive switching ratio from the potential drop and screening effect. The relationship between A-site vacancy generation resulting in surface segregation of SrO_y and resistive switching behavior was also investigated by energy resolved x-ray photoelectron spectroscopy, O 1s near edge x-ray absorption spectroscopy, and current voltage measurement.