  We consider the problem of particle tunneling through a periodically driven
ferromagnetic quantum barrier connected to two leads. The barrier is modeled by
an impurity site representing a ferromagnetic layer or quantum dot in a
tight-binding Hamiltonian with a local magnetic field and an AC-driven
potential, which is solved using the Floquet formalism. The repulsive
interactions in the quantum barrier are also taken into account. Our results
show that the time-periodic potential causes sharp resonances of perfect
transmission and reflection, which can be tuned by the frequency, the driving
strength, and the magnetic field. We demonstrate that a device based on this
configuration could act as a highly-tunable spin valve for spintronic
applications.
