Interfacial Ion Intermixing Effect on Four-Resistance States in La_0.7Sr_0.3MnO₃/BaTiO₃/La_0.7Sr_0.3MnO₃ Multiferroic Tunnel Junctions

Abstract

A multiferroic tunnel junction (MFTJ), employing a ferroelectric barrier layer sandwiched between two ferromagnetic layers, presents at least four resistance states in a single memory cell and therefore opens an avenue for the development of the next generation of high-density nonvolatile memory devices. Here, using the all-perovskite-oxide La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 as a model MFTJ system, we demonstrate asymmetrical Mn-Ti sublattice intermixing at the La0.7Sr0.3MnO3/BaTiO3 interfaces by direct local measurements of the structure and valence, which reveals the relationship between ferroelectric polarization directions and four-resistance states, and the low temperature anomalous tunneling behavior in the MFTJ. These findings emphasize the crucial role of the interfaces in MFTJs and are quite important for understanding the electric transport of MFTJs as well as designing high-density multistates storage devices.

Prospects of spintronics based on 2D materials

“…The resistance versus magnetic field curves, measured at 50 K and different polarizations of the ferroelectric layer, show clearly four distinct nonvolatile states. MFTJ and related physics of multiferroic junctions have been actively investigated both theoretically and experimentally . Recently, it was demonstrated that by further considering noncollinear magnetization alignments between the FM layers, MFTJ device with eight nonvolatile resistance states can be realized .…”

Resistive Switching and Redox Process at the BaTiO3/(La,Sr)MnO3 Multiferroic‐Type Interface

“…At an even higher level of complexity, are found the multiferroic heterostructures in which the ferroelectric barrier is incorporated between two ferromagnetic electrodes. [37][38][39] Such systems prefigure four-states memories, or in case of magnetoelectric coupling, the control of the magnetic states by an electrical field. The perovskite-type ABO 3 oxides family is tremendously rich and may provide for planar structures the metallic electrodes, the ferromagnetic ones, as well as the ferroelectric barriers.…”

“…Two oxides are particularly important: the La 1−x Sr x MnO 3 (LSMO) manganite with x close to 0.33, which couples ferromagnetism with high-spin polarization (≈100%) and metallicity, and the insulating BaTiO 3 (BTO) oxide, whose gap is 3.2 eV, as the archetype of ferroelectrics. Their growth and use within different types of stacking are largely reported, [16,25,[37][38][39][40][41] although their direct association as a multiferroic system is comparatively less documented. Both TMR and TER effects have recently been reported for the LSMO/ BTO/LSMO junction.…”

“…Both TMR and TER effects have recently been reported for the LSMO/ BTO/LSMO junction. [39] We aim here at bringing further insights in the understanding of the multiferroic-type BTO/LSMO junction. We investigate successively the ferromagnetism and related metallicity of the LSMO layer, the ferroelectricity of the BTO layer, the resistive switching of a thick Au/BTO/LSMO structure using Au as top electrodes, and finally, the atomic-scale structure and chemical composition at the lower interface.…”

Four‐state memory based on ferroelectric tunnel junctions with double ferroelectric layers

“…One classic example is multiferroic tunnel junctions (MFTJs), in which the co‐existence of the tunneling magnetoresistance (TMR) and TER effects causes them to have four resistance states . Huang et al studied the interfacial ion intermixing effect on four‐resistance states La 0.7 Sr 0.3 MnO 3 /BaTiO 3 /La 0.7 Sr 0.3 MnO 3 MFTJs , and they also demonstrated that eight resistance states can be obtained in these all‐perovskite‐oxide systems based on four magnetic configurations experimently . Theoretical work shows that switching of the antiferromagnetic order parameter in the barrier in applied electric field by means of the magnetoelectric coupling can lead to a substantial change of the resistance in MFTJs consisting of ferromagnetic electrodes and magnetoelectric antiferromagnetic barriers .…”