Mechanical force involved multiple fields switching of both local ferroelectric and magnetic domain in a Bi5Ti3FeO15 thin film

Abstract

Multiferroics have received intense attention due to their great application potential in multi-state information storage devices and new types of sensors. Coupling among ferroic orders such as ferroelectricity, (anti-)ferromagnetism, ferroelasticity and so on will enable dynamic interaction between these ordering parameters. Direct visualization of such coupling behavior in single-phase multiferroic materials is highly desirable for both applications and fundamental study. Manipulation of both ferroelectric and magnetic domains of Bi5Ti3FeO15 thin film using electric field and external mechanical force is reported, which confirms the magnetoelectric coupling in Bi5Ti3FeO15, indicates the electric and magnetic orders are coupled through ferroelasticity. Due to the anisotropic relaxation of ferroelastic strain, the back-switching of out-of-plane electric domains is not as obvious as in-plane. An inevitable destabilization of the coupling between elastic and magnetic ordering happens because of the elastic strain relaxation, which result in a subsequent decay of magnetic domain switching. Mechanical force applied on the surface of Bi5Ti3FeO15 film generates by an atomic force microscopy tip will effectively drive a transition of the local ferroelastic strain state, reverse both the polarization and magnetization in a way similar to an electric field. Current work provides a framework for exploring cross-coupling among multiple orders and potential for developing novel nanoscale functional devices. The sharp tip of a scanning probe microscope has helped researchers both visualize and manipulate domains in multiferroic thin films. Bismuth-layered oxides, such as Bi5Ti3FeO15 film, may serve as next-generation memory devices because they have nanoscale structures that can be switched by applying electrical impulses. Tingting Jia from the National Institute for Materials Science in Japan and colleagues have now discovered another way to control ferroelectric and magnetic domains in Bi5Ti3FeO15 – applying a mechanical force. Direct imaging revealed that applying a vertical force to bismuth-based samples induced spontaneous ferroelastic strain forces that coupled to magnetoelastic domains in the film. These interactions enabled the team to write surface patterns with an electrified probe tip and then reverse them through probe contact – a possible mechanical solution to electrical switching problems in high-density data storage. Mechanical force applied on the surface of Bi5Ti3FeO15 film generates by an AFM tip will effectively drive a transition of the local ferroelastic strain state, reverse both the polarization and magnetization in a way similar to an electric field. Manipulation of both ferroelectric and magnetic domains of Bi5Ti3FeO15 thin film using electric field and external mechanical force is reported, which confirms the magnetoelectric coupling in Bi5Ti3FeO15, indicates the electric and magnetic orders are coupled through ferroelasticity. Current work provides a framework for exploring cross-coupling among multiple orders and potential for developing novel nanoscale functional devices.