Phase control of magnetic state of graphite thin films by electric field

Based on first-principle total-energy calculations, we have found that by applying an external electric field it is possible to control the magnetic state of graphite thin film with the rhombohedral stacking arrangement. When exposed to a moderate electric field normal to the film, the surface of a thin film of rhombohedral graphite undergoes a magnetic phase transition from the antiferromagnetic state to the ferromagnetic state. The polarized electron spin is primarily distributed in the bottommost layer of the film, which forms the interface with the negative electrode. The amount of polarized electron spin is calculated to be 0.067 mu(B)/nm(2). The ferromagnetic ordering with the characteristic distribution of the polarized electron spin opens the possibility of using graphite thin films in electronic devices with spin degree of freedom. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3455069]