▎ 摘　　要

An analysis of a magnetic field sensor based on a graphene spin capacitor is presented. The proposed device consists of graphene nanoribbons on top of an insulator material connected to a ferromagnetic source/drain. The time evolution of spin polarized electrons injected into the capacitor can be used for an accurate determination at room temperature of external magnetic fields. Assuming a spin relaxation time of 100 ns, magnetic fields on the order of similar to 10 mOe may be detected at room temperature. The observational accuracy of this device depends on the density of magnetic defects and spin relaxation time that can be achieved. (C) 2010 American Institute of Physics. [doi:10.1063/1.3462297]