Spin-torque critical current of graphene-based lateral spin valves

• The spin-torque induced magnetization dynamics of graphene LSV is investigated.
• The tunnel contact can effectively reduce the spin-torque critical current compared to the case of transparent contact.
• The critical current to switch the magnetization from AP to P state is much smaller than that of the case from P to AP state.

In this paper the spin transfer torque (STT) induced magnetization dynamics of graphene-based lateral spin valve (LSV) structures is investigated theoretically by using the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. Effect of parameters of the LSV, contact types between the ferromagnet and graphene on the STT critical current of magnetization switching in the free layer of the LSV are studied. The polarized current which is transformed from the injector to the detector (free layer) is calculated by the analytical expressions. The results show that, from the viewpoint of application as magnetic switch, tunnel contact can effectively reduce the spin torque critical current compared to the case of transparent contact. In addition, the spin-torque critical current can also be reduced by imposing a weak magnetic field, or reducing the spacing between the injector and detector. Another important feature found from the results is that, the magnetization reversal between the parallel and anti-parallel states is asymmetric, which is in agreement with the reports in literatures.