Characterization of the Magnetism of Lycopodium Spores

The magnetic properties of Lycopodium powders from two different sources are investigated. In addition to a characteristic diamagnetism with χ = -8(1) × 10^-6, there is a Curie-law paramagnetism, which is the dominant contribution to the susceptibility below 20 K, and an additional weak hysteretic signal with a saturation magnetization of magnitude 0.6-1.8 × 10^-3 Am² kg^-1 at room temperature. After ignition of the powder, the remaining inorganic ash represents just 1.05% of the original mass, but the room temperature magnetization increases only by a factor of 5. The iron content of the Lycopodium, deduced by chemical analysis of the ash is 43-76 ppm. Of this, roughly 3/4 is paramagnetic, and 1/4 is in the form of magnetite.