Noncontact spatiotemporal strain mapping of composite multiferroic cylinders

Abstract

Recently, the reinvigoration of research interest in in strain-mediated composite multiferroic structures resulted in translational magnetoelectric devices with superior performance than their traditional counterparts. Full-filed measurements and visualization of mechanical strain, with a focus at the interface, offer new possibilities for the advancement of magnetoelectric devices regardless of the material system. Here, we report spatiotemporal strain maps of composite magnetoelectric cylinders using a novel approach combining stable laser ultrasonic vibrometer and 2D motion system measurement technique. The physical measurement technique is augmented with a robust analysis algorithm that capable of effectively and consistently detect the interface. With the spatiotemporal maps, we forecast additional utility through the concurrent extraction of polarization and magnetization maps; hence highlighting the complex interactions between the involved order parameters. Understanding the converse magnetoelectric response in strain-mediated composite multiferroics is essential for the development of devices such and motors, antennas, and wireless power transferors. Given the dependence of the converse magnetoelectric response on the strain generation and transduction, mapping the mechanical response is essential for advancement of efficient devices. This mapping approach is challenging due to the dynamic nature of the response as well as the magneto-electro-mechanical coupling. Spatiotemporal maps of in-plane and out-of plane displacement and strain components were measured concurrently off the surface of a composite structure. To generate spatiotemporal strain maps, a laser-ultrasonic vibrometer mounted on a 2D gantry system was employed to map the in-plane and out-of-plane displacement components of a strain-mediated, concentric multiferroic composite cylinder. The strain maps provided insights on the behavior of the strain mediation mechanisms within the investigated composite structure including amplification of the strain due to the disparity in the mechanical properties of the constituents, which will result in a non-uniform distribution of magnetization and polarization responses. Additionally, the method to calculate the strain maps was shown to be robust for different spatial measurement resolutions.