Atomic Surface Structures in the Chiral Magnet MnGe*

Recent interest in the B20 family of chiral magnets is driven by their ability to host novel magnetic states including skyrmions. The properties of these states may also be affected by additional DMI or anisotropy effects present at the interface of thin films which themselves depend on the atomic surface structure. Here, we present joint scanning tunneling microscopy (STM) and density functional theory (DFT) characterization of the B20 MnGe(111) surface. To determine the chemical identity of the surface, we compare atomic corrugation and dI/dV spectroscopy to DFT simulated STM images and layer resolved density of states calculations. In regions with multiple terminations present, the local chirality and stacking order of the film is established by measuring relative topographic step heights and registry of the lattices across the step. In some cases, we also resolve the helical state via spin-polarized imaging using a chromium tip. This allows us to correlate changes in the direction or periodicity of the helices to differences in the surface structures such as strain and termination.