Electric field driven domain wall transfer in hybrid structures
Domain wall (DW) motion devices attracts much interest with their prospective logic and memory applications[1][2]. Present on-chip DW manipulations by a magnetic field of electric currents or electron spin torque raise the problem of high Ohmic energy losses. We show that such a difficulty can be avoided by applying an exchange field H eff to the magnetic layer from the proximate graphene (Gr), instead of using an actual magnetic field. H eff is shown to be dependent on carrier density gradient in Gr, which is easily manipulated with a gate voltage. A novel memory device implementing this concept is designed and modeled, demonstrating switching power well below femto-Joule while maintaining…
Carrier-induced ferromagnetism in two-dimensional magnetically doped semiconductor structures
We show theoretically that the magnetic ions, randomly distributed in a two-dimensional (2D) semiconductor system, can generate a ferromagnetic long-range order via the RKKY interaction. The main physical reason is the discrete (rather than continuous) symmetry of the 2D Ising model of the spin-spin interaction mediated by the spin-orbit coupling of 2D free carriers, which precludes the validity of the Mermin-Wagner theorem. Further, the analysis clearly illustrates the crucial role of the molecular field fluctuations as opposed to the mean field. The developed theoretical model describes the desired magnetization and phase-transition temperature ${T}_{c}$ in terms of a single parameter, na…