Deterministic and robust room-temperature exchange coupling in monodomain multiferroic BiFeO3 heterostructures

Abstract

Exploiting multiferroic BiFeO3 thin films in spintronic devices requires deterministic and robust control of both internal magnetoelectric coupling in BiFeO3, as well as exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer. Previous reports utilized approaches based on multi-step ferroelectric switching with multiple ferroelectric domains. Because domain walls can be responsible for fatigue, contain localized charges intrinsically or via defects, and present problems for device reproducibility and scaling, an alternative approach using a monodomain magnetoelectric state with single-step switching is desirable. Here we demonstrate room temperature, deterministic and robust, exchange coupling between monodomain BiFeO3 films and Co overlayer that is intrinsic (i.e., not dependent on domain walls). Direct coupling between BiFeO3 antiferromagnetic order and Co magnetization is observed, with ~ 90° in-plane Co moment rotation upon single-step switching that is reproducible for hundreds of cycles. This has important consequences for practical, low power non-volatile magnetoelectric devices utilizing BiFeO3.

Structure, Performance, and Application of BiFeO3 Nanomaterials

“…The MPB in which rhombohedral and tetragonal phases coexist is thought to be for 0.67BFO-0.33BTO. Another solid solution of BFO formed with BiCoO 3 was also studied systematically [28,29,68,69]. Furthermore, a detailed crystal structure analysis of BiFe 1−x Co x O 3 was performed [68].…”

A Short Review on Verwey Transition in Nanostructured Fe3O4 Materials

“…Some multiferroic heterostructures have been produced by compound ferromagnetics (Fe 3 O 4 ) with ferroelectrics BaTiO 3 [59], Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) [60], PdZr x Ti 1-x O 3 (PZT) [61], BiFeO 3 [62], HoMnO 3 , and YMnO 3 [63]. These multiferroic heterostructures show the strong interfacial magnetoelectric effects [64][65][66][67][68][69], which can be used in Electric-field-controlled magnetism and VT in highly correlated Fe 3 O 4 materials have generated great interest recently both scientifically and technologically [51]. Ferroelastic strain control of VT was observed in epitaxial Fe 3 O 4 thin films grown on PMN-PT (011) substrate [4], as shown in four-point geometry (Figure 10(a)).…”

Interfacial Strain Gradients Control Nanoscale Domain Morphology in Epitaxial BiFeO3 Multiferroic Films

“…[ 53,65 ] , such an asymmetry in the spectrum suggests that the magnetic arrangement is more complex than simple collinear antiferromagnetism. Guided by previous observations for films under similar levels of strain, [ 47,66 ] we have successfully fit the spectrum with a model corresponding to a (slightly) anharmonic cycloid (with anharmonicity along the propagation direction, and parameter of m = 0.5) with a tilting of the cycloid plane (of about 5°) toward the in‐plane direction (full details given in the Supporting Information).…”