Engineering the Dzyaloshinskii-Moriya interaction in Mn_xFe_1-xGe thin films

Controlling chiral interactions in B20-hellimagnet systems is an exciting route to tailoring topological spin textures, e.g. Bloch skyrmions, in these systems. Forming Mn_xFe_1-xGe alloys enable this control by varying x, which was previously studied using Lorentz transmission electron microscopy and neutron scattering studies on bulk Mn_xFe_1-xGe crystals [1,2]. Thin film versions of this material enable spintronic devices that take advantage of non-collinear spin textures, however, the growth of Mn_xFe_1-xGe compounds has been an outstanding challenge. Here we report the successful MBE growth and comprehensive characterization of epitaxial Mn_xFe_1-xGe films. In addition, in concert with micromagnetic simulations, we use microwave absorption spectroscopy to quantify the Dzyaloshinskii-Moriya interaction. Our approach also tests the limits of micromagnetic computational treatment of a helimagnets in which the helical pitch is comparable to a lattice constant.
[1] K. Shibata et al., Nat. Nanotechnol. 8, 723 (2013).
[2] S. V. Grigoriev et al., Phys. Rev. Lett. 110, 207201 (2013).