ABO3 multiferroic perovskite materials for memristive memory and neuromorphic computing

The unique electron spin, transfer, polarization and magnetoelectric coupling characteristics of ABO₃ multiferroic perovskite materials make them promising candidates for application in multifunctional nanoelectronic devices. Reversible ferroelectric polarization, controllable defect concentration and domain wall movement originated from the ABO₃ multiferroic perovskite materials promotes its memristive effect, which further highlights data storage, information processing and neuromorphic computing in diverse artificial intelligence applications. In particular, ion doping, electrode selection, and interface modulation have been demonstrated in ABO₃-based memristive devices for ultrahigh data storage, ultrafast information processing, and efficient neuromorphic computing. These approaches presented today including controlling the dopant in the active layer, altering the oxygen vacancy distribution, modulating the diffusion depth of ions, and constructing the interface-dependent band structure were believed to be efficient methods for obtaining unique resistive switching (RS) behavior for various applications. In this review, internal physical dynamics, preparation technologies, and modulation methods are systemically examined as well as the progress, challenges, and possible solutions are proposed for next generation emerging ABO₃-based memristive application in artificial intelligence.

Tunable magnetization steps in mixed valent ferromagnet Eu2CoMnO6

Magnetic properties can be manipulated to enhance certain functionalities by tuning different material processing parameters. Here, we present the controllable magnetization steps of hysteresis loops in double-perovskite single crystals of Eu2CoMnO6. Ferromagnetic order emerges below TC ≈ 122 K along the crystallographic c axis. The difficulty in altering Co2+ and Mn4+ ions naturally induces additional antiferromagnetic clusters in this system. Annealing the crystals in different gas environments modifies the mixed magnetic state, and results in the retardation (after O2-annealing) and bifurcation (after Ar-annealing) of the magnetization steps of isothermal magnetization. This remarkable variation offers an efficient approach for improving the magnetic properties of double-perovskite oxides.

Strong magnetoelectric coupling in mixed ferrimagnetic-multiferroic phases of a double perovskite

Exploring new magnetic materials is essential for finding advantageous functional properties such as magnetoresistance, magnetocaloric effect, spintronic functionality, and multiferroicity. Versatile classes of double perovskite compounds have been recently investigated because of intriguing physical properties arising from the proper combination of several magnetic ions. In this study, it is observed that the dominant ferrimagnetic phase is coexisted with a minor multiferroic phase in single-crystalline double-perovskite Er₂CoMnO₆. The majority portion of the ferrimagnetic order is activated by the long-range order of Er³⁺ moments below T_Er = 10 K in addition to the ferromagnetic order of Co²⁺ and Mn⁴⁺ moments arising at T_C = 67 K, characterized by compensated magnetization at T_Comp = 3.15 K. The inverted magnetic hysteresis loop observed below T_Comp can be described by an extended Stoner-Wohlfarth model. The additional multiferroic phase is identified by the ferroelectric polarization of ~0.9 μC/m² at 2 K. The coexisting ferrimagnetic and multiferroic phases appear to be strongly correlated in that metamagnetic and ferroelectric transitions occur simultaneously. The results based on intricate magnetic correlations and phases in Er₂CoMnO₆ enrich fundamental and applied research on magnetic materials through the scope of distinct magnetic characteristics in double perovskites.