Manipulation of the spin helix in FeGe thin films and FeGe/Fe multilayers

Abstract

Magnetic materials without structural inversion symmetry can display the Dzyaloshinskii-Moriya interaction, which manifests itself as chiral magnetic ground states. These chiral states can interact in complex ways with applied fields and boundary conditions provided by finite sample sizes that are of the order of the lengthscale of the chiral states. Here we study epitaxial thin films of FeGe with a thickness close to the helix pitch of the helimagnetic ground state, which is about 70 nm, by conventional magnetometry and polarized neutron reflectometry. We show that the helix in an FeGe film reverses under the application of a field by deforming into a helicoidal form, with twists in the helicoid being forced out of the film surfaces on the way to saturation. An additional boundary condition was imposed by exchange coupling a ferromagnetic Fe layer to one of the interfaces of an FeGe layer. This forces the FeGe spins at the interface to point in the same direction as the Fe, preventing node expulsion and giving a handle by which the reversal of the helical magnet may be controlled.

References in corpus (5)

• Extended elliptic skyrmion gratings in epitaxial MnSi thin films
• Scattering mechanisms in textured FeGe thin films: magnetoresistance and the anomalous Hall effect
• Metallic State in Cubic FeGe beyond its Quantum Phase Transition
• Strain-induced effects on the magnetic and electronic properties of epitaxial Fe${}_{1-x}$Co${}_x$Si thin films
• Giant topological Hall effect in strained Fe${}_{0.7}$Co${}_{0.3}$Si epilayers

Cited by in corpus (9)

• Static Hopf Solitons and Knotted Emergent Fields in Solid-State Noncentrosymmetric Magnetic Nanostructures
• Chiral Bobbers and Skyrmions in Epitaxial FeGe/Si(111) Films
• Three-dimensional chiral skyrmions with attractive interparticle interactions
• Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe${}_{1-y}$Co${}_y$Ge films
• Dynamics of skyrmionic states in confined helimagnetic nanostructures
• Chiral magnetic excitations in FeGe films
• Metastable solitonic states in the strained itinerant helimagnet FeGe
• Classification of magnetic inhomogeneities and $0-\pi$ transitions in superconducting-magnetic hybrid structures
• A Spiral Spin State with Open Boundary Conditions in a Magnetic Field