Emergent Magnetic Skyrmions in a Topological Weyl Nodal Ring Semimetal

Topological magnetic materials are expected to show multiple transport responses because of their unusual bulk electronic topology in momentum space and their topological spin texture in real space. However, such multiple topological properties-hosting materials are rare in nature. In this work, we unambiguously reveal the emergence of magnetic skyrmions in Mn5Ge3 single crystal through detailed electrical transport and Lorentz transmission electron microscopy (L-TEM) combined with ab initio calculations. We demonstrate that Mn5Ge3 is a topological ferromagnet with multiple nodal rings in its electronic structure. Importantly, L-TEM experiments further reveal that the magnetic skyrmions appear in the (001) plane when an appropriate magnetic field is applied along the [001] direction. Skyrmion-induced topological Hall resistivity as large as ∼972 nΩ cm is also observed over a wide temperature-magnetic field region. These prove Mn5Ge3 as a rare magnetic topological nodal-ring semimetal with great significance to explore novel topological multifunctionality, which facilitate the development of spintronics.