Reduced switching current density in spin transfer torque with lateral symmetry breaking structure

We find a noticeable reduction of the spin transfer torque switching current density in a lateral symmetry breaking structure by employing micromagnetic simulation. We investigate the detailed spin dynamics in a conventional magnetic tunneling junction structure with an ellipse shape; the switching occurs with incoherent spin rotation by forming irregular spin configurations. By introducing the proper asymmetry of the lateral shape of a magnetic tunneling junction, a more efficient coherent spin rotation mode is easily excited and the switching current density shows a 30-40% reduction.