Random magnetism of superhigh surface area carbon having minute graphitic structures

The magnetic properties of micrographitic structure-oriented carbons with different surface areas were examined over the temperature range of 1.7 to 300 K. Superhigh surface area carbon of specific surface area = 3110 m2 g−1, whose surface atom ratio is 0.94, showed a remarkable magnetic hysteresis and ξ−T relation with maximum below 4.2 K. The magnetic hysteresis depended on the measuring temperature; the residual magnetization was 0.016 emu G g−1 at 1.7 K and 0.015 emu G g−1 at 300 K. The ferromagnetic behavior was dependent on the measuring time, and thereby the maximum of the ξ−T relation shifted to lower temperature with a longer measuring time. On the contrary, low surface area carbon of surface area = 570 m2 g−1 showed no ferromagnetism.