Using neutrons to measure the helix pitch for calculating the Topological Hall Effect
07 Jan 2020







Skyrmions are the focus of intense research for their potential applications in spintronics: next-generation electronic devices that exploit the spin degree of freedom. Skyrmions are curious magnetic systems and offer the possibility of new high-density, low-power magnetic storage devices.

Previous research has shown that the conditions required for the formation of skyrmions occur in a group of materials called B20 compounds, which naturally possess the necessary inversion symmetry in their crystal structure. In research published in Physical Review B, an international team of researchers used polarised neutron reflectometry (PNR) on the POLREF beamline to investigate the preliminary helical magnetic phase in B20 thin films.

Their pioneering use of PNR on POLREF allowed them to study the underlying helical magnetic structure, by determining the magnetic depth profile of the film. They were able to measure the helix pitch of the spiral: the distance in which it completes one 'twist'. They were also able to observe the changes in the helix pitch with increasing concentrations of cobalt. Their results provide a comprehensive data set for the magnetic properties of Fe1−yCoyGe B20 films and demonstrate that it is possible to control the helix pitch, a crucial step towards developing working devices.

Related publication: “Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20" Phys. Rev. B, 2018, 97, 214406, DOI: 10.1103/PhysRevB.97.214406

Authors: Charles S. Spencer (University of Leeds), Jacob Gayles (Max Planck Institute for Chemical Physics of Solids; Johannes Gutenberg Universität Mainz), Nicholas A. Porter (University of Leeds), Satoshi Sugimoto (University of Leeds), Zabeada Aslam (University of Leeds), Christian J. Kinane (ISIS), Timothy R. Charlton (ISIS), Frank Freimuth (Forschungszentrum Jülich), Stanislav Chadov (Max Planck Institute for Chemical Physics of Solids), Sean Langridge (ISIS), Jairo Sinova (Johannes Gutenberg Universität Mainz; Institute of Physics ASCR), Claudia Felser (Max Planck Institute for Chemical Physics of Solids), Stefan Blügel (Forschungszentrum Jülich), Yuriy Mokrousov (Johannes Gutenberg Universität Mainz; Forschungszentrum Jülich), and Christopher H. Marrows (University of Leeds).

Instrument: Polref​

Contact: de Laune, Rosie (STFC,RAL,ISIS)