Academic Affiliation: The Ohio State University

Research Area: Low-Temperature Scanning Tunneling Microscopy

Magnetic Textures in Chiral Magnet MnGe Observed with SP-STM

Materials with non-centrosymmetric crystal structures can host chiral spin states including magnetic skyrmions. Bulk MnGe hosts a short period magnetic state (3 nm), whose structure depends strongly on atomic lattice strain, and shows a large emergent transport signature associated with the skyrmion phase. Here, we use low-temperature (5 K) spin-polarized scanning tunneling microscopy (SP-STM) to image the magnetic textures in MnGe thin films grown via molecular beam epitaxy and study the influence of the surface on those textures. Most microscopic locations show a spin spiral phase with a 6-8 nm period and a propagation direction that is influenced by step edges, surface termination, and strain. We also report the presence of isolated target skyrmions that likely form due to local modulations in the atomic structure. The skyrmions have a triangular shape which appears to be set by the in-plane lattice vectors, and a core size of approximately 15 nm. We observe the target state is significantly more sensitive to magnetic fields than the spiral phase, and that local voltage and current pulses with the STM tip imply the texture can be ‘switched’ between states with different topological charge. To fully understand the magnetic textures in MnGe we will expand this study by investigating films of different thicknesses to vary the magnetic anisotropy.