Direct evidence for the spin cycloid in strained nanoscale bismuth ferrite thin films
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Date
2017-01-31
Journal Title
Journal ISSN
Volume Title
Publisher
Australian Institute of Physics
Abstract
Multiferroic materials demonstrate excellent potential for next-generation multifunctional devices, as they exhibit coexisting ferroelectric and magnetic orders. Bismuth ferrite (BiFeO3) is a rare exemption where both order parameters exist far beyond room temperature, making it the ideal candidate for technological applications. In particular, magnonic devices that utilize electric control of spin waves mediated by complex spin textures are an emerging direction in spintronics research. To realize magnonic devices, a robust long-range spin cycloid with well known direction is desired, since it is a prerequisite for the magnetoelectric coupling. Despite extensive investigation, the stabilization of a large-scale uniform spin cycloid in nanoscale (100 nm) thin BiFeO3 films has not been accomplished. Here, we demonstrate cycloidal spin order in 100 nm BiFeO3 thin films through the careful choice of crystallographic orientation, and control of the electrostatic and strain boundary conditions during growth [1]. Neutron diffraction, in conjunction with X-ray diffraction, reveals an incommensurate spin cycloid with a unique [112] propagation direction. While this direction is different from bulk BiFeO3, the cycloid length and Néel temperature remain equivalent to bulk single crystals. The discovery of a large scale uniform cycloid in thin film BiFeO3 opens new avenues for fundamental research and technical applications that exploit the spin cycloid in spintronic or magnonic devices.
Description
Keywords
Spin, Bismuth, Ferrite, Thin films, Materials, Order parameters, Ambient temperature, Spin waves, Magnons, Neel temperature
Citation
Bertinshaw, J., Maran, R., Callori, S. J., Ramesh, V., Cheung, J., Danilkin, S. A., Lee, W. T., Hu, S., Seidel, J., Valanoor, N., & Ulrich, C. (2017). Direct evidence for the spin cycloid in strained nanoscale bismuth ferrite thin films. Poster presented to the 41st Annual Condensed Matter and Materials Meeting, 31st January - 3rd February 2017 Charles Sturt University Wagga Wagga, NSW, Australia. (pp. 79). Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2017/Wagga_2017_Conference_Handbook.pdf