Performance Enhancement and In Situ Observation of Resistive Switching and Magnetic Modulation by a Tunable Two-Level System of Mn Dopants in a-Gallium Oxide-based Memristor

Purely gallium oxide-based memristors (GOMRs) show great potentials in resistive random-access-memory (RRAM) due to their chemical stability and resistive switching characteristics with R-off/R-on ratios up to 10(2); indeed, GOMRs with higher R-off/R-on ratios and more functionalities are more expected. In this study, ferromagnetic amorphous gallium oxide (a-GMO) films with a tunable two-level system of Mn dopants, i.e., Mn2+ and Mn3+ ions, are prepared by scalable polymer assisted deposition. The Pt/a-GMO/Pt memristors show a high Roff/Ron ratio of 103, at least one order of magnitude higher than those of previously reported purely GOMRs, thanks to the abundant oxygen vacancies (V(O)s)-induced low resistance state and Mn2+-enhanced high resistance state. Meanwhile, magnetic modulation (MM) is realized electrically in the a-GOMRs during the RS, through the tuning of bound magnetopolarons (BMPs) by bias voltage-induced VOs variations, which may be useful for quaternary information coding. Notably, the transition between Mn3+ and Mn(2+)ions is observed in the GOMRs, which is closely related to the variations of V-O concentration and BMP amount, providing an in situ tool to probe the V-O-induced RS and BMP-dependent MM. The results give insights to Mn-doped GOMRs and may be useful for design, fabrication, and testing of multifunctional high-performance RRAMs.

Automated summary

In this study, ferromagnetic amorphous gallium oxide (a-GMO) films with tunable Mn dopants were prepared. The Pt/a-GMO/Pt memristors showed a high Roff/Ron ratio of 103, thanks to the low resistance state induced by oxygen vacancies (VOs) and the high resistance state enhanced by Mn2+. Magnetic modulation (MM) was achieved electrically through tuning of bound magnetopolarons (BMPs) by bias voltage-induced VOs variations, which may have applications in quaternary information coding. The transition between Mn3+ and Mn2+ ions in the GOMRs was observed, providing an in situ tool to study the V-O induced resistive switching and BMP-dependent MM.