Magnetic vortex state in a layered muscovite sheet silicate single crystal

Natural muscovite, also called white-mica—a member in the sheet silicate mineral family, has been successfully exfoliated down to few mono-layers by mechanical exfoliation technique. The exfoliated muscovite single crystal flakes have been successfully transferred onto various substrates. Atomic force microscopy study was performed on exfoliated flakes transferred onto glass substrates; the thinnest flake measured had a thickness of ∼4.9 nm. Analysis made on the muscovite crystal structure and cleavage property clearly proved that the muscovite is another kind of layered 2D-material similar to graphene, MoS₂, NiPS₃ etc. Infrared absorption, diffuse reflectance and Raman spectroscopy studies were carried out. Muscovite exhibited an optical energy wide-band gap of ∼4.65 eV and exhibited a high intense Raman mode at 3620 cm⁻¹, which we report here, for the first time. As the muscovite contains Fe, it exhibited interesting anisotropic magnetization properties. The field dependent magnetization showed signatures which well resembles that of an in-plane magnetic vortex state, normal and twisted onion states of magnetization configurations. (paper)