Preparation of ferromagnetic pyrolytic carbon by heating under magnetic field and its physical properties

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We have prepared pyrolytic carbon samples from triethylamine by pyrolysis under high magnetic field up to 6 Tesla, and investigated their magnetic properties. Ferromagnetic samples were obtained from the pyrolysis products even at room temperature. The maximum spontaneous magnetization was 3.0 emu/g at 300K. The crystal structure was examined by the synchrotron X-ray diffraction experiment at SPring-8. The diffraction peak of diamond was observed for the ferromagnetic samples. Thus, it is possible that the ferromagnetic ordering of radical spins is caused by defects in the diamond structure. The diffraction peak intensity of diamond for the ferromagnetic samples increased with the applied magnetic field at sample preparation. Therefore, the magnetic field may help to form a three dimensional ferromagnetic structure in the carbon-based ferromagnet. A ferromagnetic sample with higher magnetization of 6.4emu/g at 300K was also obtained by field-pyrolysis with diamond powder under magnetic field of 6 Tesla. The crystal growth of the ferromagnetic pyrolytic carbon may be accelerated on the diamond powder, which is consistent with the above-mentioned synchrotron X-ray diffraction result.