Resistive switching in FeNi/Al2O3/NiO/Pt structure with various Al2O3 layer thicknesses

Abstract

Abstract Noble metals are generally used as electrodes in resistive switching devices. In this work, ferromagnetic metallic NiFe is used as top electrode on NiO films, and stable unipolar resistive switching (URS) behavior has been observed after a forming process. By inserting a thin Al2O3 layer between NiFe and NiO, URS persists with increasing the thickness of Al2O3 layer up to 20 nm. The URS behavior can be attributed to the formation and rupture of metallic Ni filaments in NiO layer, which penetrate through the thin Al2O3 layer, and have been confirmed by the observation of anisotropic magnetoresistance. With further increasing the thickness of Al2O3 layer up to 30 nm, forming free bipolar resistive switching (BRS) behavior is observed, which is due to the oxygen vacancy accumulation and dissipation at the interface because the thick Al2O3 layer blocks the penetration of Ni filaments. By inserting a thin Al2O3 layer with thickness below 20 nm, the distribution of the reset voltages in URS is significantly narrowed.