Domains and domain walls in multiferroics

Abstract

Multiferroics are materials combining several ferroic orders, such as ferroelectricity, ferro- (or antiferro-) magnetism, ferroelasticity and ferrotoroidicity. They are of interest both from a fundamental perspective, as they have multiple (coupled) non-linear functional responses providing a veritable myriad of correlated phenomena, and because of the opportunity to apply these functionalities for new device applications. One application is, for instance, in non-volatile memory, which has led to special attention being devoted to ferroelectric and magnetic multiferroics. The vision is to combine the low writing power of ferroelectric information with the easy, non-volatile reading of magnetic information to give a “best of both worlds” computer memory. For this to be realised, the two ferroic orders need to be intimately linked via the magnetoelectric effect. The magnetoelectric coupling – the way polarization and magnetization interact – is manifested by the formation and interactions of domains and domain walls, and so to understand how to engineer future devices one must first understand the interactions of domains and domain walls. In this article, we provide a short introduction to the domain formation in ferroelectrics and ferromagnets, as well as different microscopy techniques that enable the visualization of such domains. We then review the recent research on multiferroic domains and domain walls, including their manipulation and intriguing properties, such as enhanced conductivity and anomalous magnetic order. Finally, we discuss future perspectives concerning the field of multiferroic domain walls and emergent topological structures such as ferroelectric vortices and skyrmions.

Roadmap on Magnetoelectric Materials and Devices

“…However, this will not happen in the near future without substantial efforts in bulk material synthesis, characterization and modeling. The new possibilities for electric and magnetic domain imaging, summarized in two recent reviews [64,119], may contribute to these efforts, hopefully helping to transfer the most promising materials and phenomena to thin films. In parallel, it is important to pursue the investigation of other near-RT bulk multiferroic materials (such as CuO [120] and the ferrimagnetic family Ga2-xFexO3 [121,122]), and materials such as -Fe2O3 where RT multiferroicity has only been reported in nanocrystalline or thin-film form [123].…”

Emergent properties at oxide interfaces controlled by ferroelectric polarization

“…Seidel et al first directly observe the conductivity at DWs in BFO; they found that 180°and 109°DWs in multiferroic BiFeO 3 thin films are conductive at room temperature while the 71°DWs are non-conducting 123 . Numerous studies on DW conductivity have been carried out since then 129,130 . One mechanism of non-charged DW conductivity is from the inhomogeneous elastic strains.…”

Crackling noise and avalanches in minerals

“…A second development relates to the current in domain walls and associated chemical changes. Ever since the discovery of superconductivity in domain walls (Aird and Salje 1998) and subsequent studies of highly conducting walls (Seidel et al 2010), the concept of domain wall electronics was developed rapidly and was reviewed by Catalan et al (2012) and Evans et al (2020).…”