Browsing by Author "Dainlkin, SA"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Direct evidence for the spin cycloid in strained nanoscale bismuth ferrite thin films
    (Australian Institute of Physics, 2017-01-31) Bertinshaw, J; Maran, R; Callori, SJ; Ramesh, V; Cheung, J; Dainlkin, SA; Lee, WT; Hu, S; Seidel, J; Valanoor, N; Ulrich, C
    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.
  • Thumbnail Image
    Item
    Inelastic neutron scattering in multiferroic materials
    (Australian Institute of Physics, 2012-02-02) Reynolds, NM; Graham, PJ; Mulders, AM; McIntyre, GJ; Dainlkin, SA; Fujioka, J; Tokura, Y; Keimer, B; Reehuis, M; Ulrich, C
    In order to obtain a deeper understanding of the spin interactions between the magnetic moments of the Tb-ions and the Mn-ions in multiferroic TbMnO3, inelastic neutron scattering experiments (at the ILL in Grenoble and the Bragg Institute at ANSTO) are performed on isostructural, non-multiferroic TbVO3. Acoustic and optical magnon branches are identified at energies comparable to the spin wave excitation spectrum of YVO3. In addition, a crystal field excitation arising from the Tb-ions is identified at the energy of 14.9 meV. This is substantially larger than the crystal field excitation at 4.5 meV in TbMnO3.