Non-volatility using materials with only volatile properties: Vertically integrated magnetoelectric heterostructures and their potential for multi-level-cell devices

Different (1–3) heterostructures, such as BiFeO3-CoFe2O4 and BiFeO3-CuFe2O4 on Pb(Mg1/3Nb2/3)0.74Ti0.26O3 (PMN-26PT), were selected for study as possible materials for magnetoelectric (ME) random access memory. The (1–3) heterostructures were deposited, and multimagnetic states were found under different E-field (E) conditions. Upon removal of E, two possible remnant magnetization states remained stable. If an H-field (H) was also applied, two additional stable remnant magnetization states were found. Our investigations demonstrate (1–3) heterostructures with nonvolatility even though the individual phases/substrates had only volatile properties. This simplifies materials selection for multistate systems based on these heterostructures, averting difficulties with compositional nonuniformity and property repeatability, in particular, with regard to PMN-xPT crystal substrates. With such N≥4 magnetic state systems, a multilevel-cell memory device could readily be built with high ME coupling and numerous accessible magnetic states.Different (1–3) heterostructures, such as BiFeO3-CoFe2O4 and BiFeO3-CuFe2O4 on Pb(Mg1/3Nb2/3)0.74Ti0.26O3 (PMN-26PT), were selected for study as possible materials for magnetoelectric (ME) random access memory. The (1–3) heterostructures were deposited, and multimagnetic states were found under different E-field (E) conditions. Upon removal of E, two possible remnant magnetization states remained stable. If an H-field (H) was also applied, two additional stable remnant magnetization states were found. Our investigations demonstrate (1–3) heterostructures with nonvolatility even though the individual phases/substrates had only volatile properties. This simplifies materials selection for multistate systems based on these heterostructures, averting difficulties with compositional nonuniformity and property repeatability, in particular, with regard to PMN-xPT crystal substrates. With such N≥4 magnetic state systems, a multilevel-cell memory device could readily be built with high ME coupling and numerous acc...