Magnetic properties of synthetic fluorophlogopite mica crystals

Micas have recently attracted the interest of materials scientists to be used as flexible substrates for the growth of nanomaterials. Synthetic fluorophlogopite is particularly appealing due to its high thermal stability and a significantly lower level of impurities compared to natural mica. Perhaps because of such high purity, little attention has been given to its magnetic properties, assumed to be diamagnetic. Herein, we report an in-depth study of the magnetic properties of commercial fluorophlogopite mica crystals as a function of magnetic field and temperature. Our study shows that the magnetic response of mica comprises diamagnetic and paramagnetic components. The latter is quite significant at low temperatures and can be analyzed within the framework of Curie's law and the Langevin theory, which indicate that it originates from isolated magnetic cations. Hence, special care must be taken to study the magnetic properties of mica-supported nanostructures. We propose a protocol to correct the magnetic contributions of mica substrates which can be useful in future developments of flexible magnetic devices.