Anomalous resistive switching effect in La0.8Ca0.2MnO3/Nb:SrTiO3 structure

Abstract

A barrier-type resistive switching (RS) unit, composed of a metal and Nb:SrTiO3 (NSTO), holds significant potential for data storage applications due to its high storage density, low operating voltage, and excellent stability. While extensive research has been conducted on conductive oxides (COs), there has been relatively less focus on the RS properties of heterogeneous structures combing CO electrodes and NSTO. Epitaxial growth of CO on NSTO is expected to yield devices with enhanced stability and repeatability. This study explores the RS characteristics of La0.8Ca0.2MnO3 (LCMO)/NSTO heterostructures through epitaxy of both conventional and anoxic LCMO films on (00 l)-oriented NSTO single crystal substrates. The results reveal that the conventional LCMO/NSTO structure exhibits a conventional counterclockwise bipolar RS (BRS) effect, while the anoxic LCMO/NSTO heterostructure demonstrates a unique clockwise (CW) BRS effect (exhibiting different RS characteristics under different applied voltages). The study concludes that the CW-BRS effect mechanism is attributed to a high concentration of oxygen vacancies (Vo) in LCMO. Under different external electric fields, Vo in LCMO and NSTO migrate to the LCMO/NSTO interface, respectively, leading to multiple changes in the interface barrier. These findings offer valuable experimental insights for utilizing CO in the field of RS applications.