Figure 6

Writing a SDW into a gate arm. (a₁) Top view and (a₂) side view of the gate arm integrated with a writing unit. The writing unit and the Pt/Co waveguide layer form a trilayer spin-valve structure. The two top electrodes supplied with a voltage, U_DC, cause an electron flow along the dotted line (the distribution of the current flowing lines in the yz plane is illustrated in Supplementary Figure 6). Initially, both the polarizer and free layer are magnetically oriented upward. Under the action of opposite torques from the spin-polarized current, the spins in the Pt/Co layer underneath the A top electrode are reversed, whereas those below the B electrode maintain the initial orientation, which introduces a SDW in between. (b) Transient states at indicated times after current launching. We have checked the influence of the density of electron current (J_z) on the injection of the reverse domain by changing J_z from 0.9 to 2.0 MA mm^-2 with an interval of 0.1 MA mm^-2 and found that the reverse domain can be reliably written into the Pt/Co layer for J_z not less than 1.1 MA mm^-2. In simulations, we focused only on spin dynamics of the free layer, and properties of the spacer and polarizer were modeled by several parameters. The spin polarization was assumed to be 0.4²⁷ and the spin orientation in the polarizer is m_p=(0, 0, 1), that is, along the +z axis. The effect of the out-of-plane (field-like) torque is negligible, as there is no difference in spin dynamics of the free layer for ξ=0 and 1.0, where ξ is the amplitude ratio of the field-like torque to the in-plane one.²⁷