Resistive switching effect in RE-Doped cobalt ferrite nanoparticles

Abstract

Spinel ferrite along with numerous important properties, also exhibit resistive switching effect. Cerium (Ce) doped Co-ferrite nanoparticles having composition CoFe2-xCexO4 (where x = 0.0, 0.05, 0.15, 0.20) were synthesized by co-precipitation synthesis route. X-ray Diffraction analysis confirmed the formation of cubic spinel phase with minor amount of impurities. Frequency dependent dielectric and electrical properties were studied at room temperature within frequency range of 20 Hz to 3 MHz. Dielectric constant, dielectric losses and AC conductivity decreases with cerium substitutions which is usual trend observed in ferrite materials. Modified Debye function was employed to fit Dielectric constant (ε′)- frequency (f) data. Jonscher's power law was employed to study AC conductivity. DC resistivity decreased with increasing temperature. DC resistivity and drift mobility decreased with cerium substitution while activation energy increased. Current–Voltage (I–V) curves of the synthesized composition were studied at room temperature. Current–Voltage (I–V) curves showed nonlinear hysteresis loop like behavior. Current follow different values for forward and reversed applied DC voltage which confirmed that resistive switching effect exit in studied samples. Sample with Ce composition x = 0.25 exhibit larger hysteresis loop than that of other compositions. This shows that sample for Ce composition x = 0.25, can be employed for nonvolatile Resistive Random-Access Memory (ReRAM) applications. Resistive switching effect was explained by utilizing Space-charge-limited current (SCLC) conduction model and by formation of a Schottky barrier at the metal-semiconductor interface.