Recently published in Nanoscale in collaboration with colleague from Greece, the RCPTM researchers reported the effect of oxidation degree on the broadband non-linear optical response and magnetic behavior of graphene oxide, as well as on a route for obtaining reduced graphene oxide with enhanced optical properties without sacrificing the high dispersibility of the parent graphene oxide. It turns out that with the rise in the number of sp3 states upon oxidation, more paramagnetic centres with localized spins evolved. On lowering the temperature, the spins order ferromagnetically at the Curie temperature the value of which was observed to increase with the degree of oxidation. Furthermore, the magnetization in the low-temperature ferromagnetic state was found to increase with the rise of the oxidation level. It is, however, speculated that if the degree of oxidation exceeds a threshold value, the ferromagnetic alignment can be lost restoring the paramagnetic behavior over the whole graphene oxide lattice.
Liaros, N.; Tucek, J.; Dimos, K.; Bakandritsos, A.; Andrikopoulos, K. S.; Gournis, D.; Zboril, R.; Couris, S. The Effect of the Degree of Oxidation on Broadband Nonlinear Absorption and Ferromagnetic Ordering in Graphene Oxide. Nanoscale 2016, 8 (5), 2908-2917. DOI: 10.1039/C5NR07832F