A Single-Spin Switch

With magnetic tunnel junctions scaling down, new phenomena due to the correlated charge transport are anticipated. One relevant phenomenon is associated to the non-avoidable traps in the insulator. In particular, the Coulomb interaction leads to a strong repulsion on a trap, a Coulomb blockade, while the Pauli blockade results in spin-dependent correlations at the transport through quantum dots and traps [1,2]. Spin-dependent hopping is responsible for large magnetoresistance in ferromagnet-insulator-metal structures [3] and magnetic tunnel junctions, due to the strong dependence of the trap occupation n and the current on the avareage spin s of the trap, which are determined by the solution of the system: d dt n = ΓS − n − ΓDn − ΓDpDs, d dt s = pSΓS − n − ΓDs − pDΓDn + [s × ωL]