title: Direct evidence for the spin cycloid in strained nanoscale bismuth ferrite thin films.
abstract: Magnonic devices that utilize electric control of spin waves mediated by complex spin textures are an emerging direction in spintronics research. Room-temperature multiferroic materials, such as bismuth ferrite (BiFeO3), would be ideal candidates for this purpose. 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. Neutron diffraction, in conjunction with X-ray diffraction, reveals an incommensurate spin cycloid with a unique [11] propagation direction. While this direction is different from bulk BiFeO3, the cycloid length and Néel temperature remain equivalent to bulk at room temperature.
authors: School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia.|The Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors: Joel
authors: J
authors: Bertinshaw
authors: School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Ronald
authors: R
authors: Maran
authors: School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia.|The Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors: Sara J
authors: SJ
authors: Callori
authors: School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Vidya
authors: V
authors: Ramesh
authors: School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Jeffery
authors: J
authors: Cheung
authors: The Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors: Sergey A
authors: SA
authors: Danilkin
authors: The Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors: Wai Tung
authors: WT
authors: Lee
authors: School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Songbai
authors: S
authors: Hu
authors: School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Jan
authors: J
authors: Seidel
authors: School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Nagarajan
authors: N
authors: Valanoor
authors: School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia.|The Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors: Clemens
authors: C
authors: Ulrich