Room temperature ferromagnetism in Co-doped amorphous carbon composites from the spin polarized semiconductor band

Abstract

This study provides conclusive evidence of room temperature ferromagnetism in Co-doped amorphous carbon (a-C) composites from the spin polarized semiconductor band. These composites are constructed from discontinuous [Co(3 nm)/a-C(dc nm)]5 multilayers with dc = 3 nm and dc = 6 nm. Only remnant circular dichroism (CD) was observed from the dc = 3 nm sample but not when dc = 6 nm. In addition, the remnant CD peaks at 5.5 eV, which is comparable with the absorption peak associated with the C σ-σ* gap transition. We suggest that the possible mechanism for this coupling can be considered as a magnetic proximity effect in which a ferromagnetic moment in the C medium is induced by Co/C interfaces.