Spin polarization properties of thiophene molecule adsorbed to the edge of zigzag graphene nanoribbon

Abstract Spin polarization properties of thiophene molecule adsorbed to the edge of zigzag graphene nanoribbon (GNR) are studied based on density functional theory calculations. It is shown that there is charge transfer between the thiophene molecule and the zigzag GNR, which changes the bond lengths of the thiophene molecule. Another consequence of the charge transfer is the spontaneous spin polarization of the thiophene molecule. The mechanism of the spontaneous spin polarization is also discussed based on the analysis of the density of states. It is found that the p orbitals of the carbon atoms and the sulfur atom in thiophene molecule become spin split near the Fermi energy, so preferential fillings of the spin-splitted p orbitals make the thiophene molecule spin polarized. This spontaneous spin polarization of thiophene molecules adsorbed to the zigzag GNR could be a new route to graphene-based organic spintronic devices.