Gate-controlled ballistic conductance of magnetic nanowires with double point contacts

Controlling the conductance and current flow through nanostructured magnetic point contacts is a key challenge for future spintronic devices. This could be achieved by exploiting the Rashba spin-orbit coupling effect induced by an external gate in the middle of two pinned domain walls at the point contacts. Here, I investigate the electrical conductance of a half-metallic diluted magnetic semiconductor nanowire with a double point contact exploitable in switching devices controlled by lateral gate voltage. The coherent quantum interference between forward and backward-scattered waves in the spin quantum well formed by the double point contact leads to quasibound states with finite lifetimes. The energetic position of these quasibound states could be adjusted by the lateral gate voltage so that the incident energy coincides with one of the quasibound energy levels in the spin quantum well. Conductance calculations in the presence of an applied electric field perpendicular to the nanowire surface exhibit typical resonant tunneling behavior, where the nanostructure switches to the low-resistance ON state by tuning the Rashba coupling strength in the range of a few tens of meV nm. This study paves the way for utilizing the gate-controlled Rashba spin-orbit coupling effect to design and develop practical spintronic devices.