  We investigate electron localization and dynamical spin locking induced by ac
magnetic fields in double quantum dots. We demonstrate that by tuning the ac
magnetic fields parameters, i.e., the field intensity, frequency, and the phase
difference between the fields within each dot, coherent destruction of
tunneling (and thus charge localization) can be achieved. We show that in
contrast with ac electric fields, ac magnetic fields are able to induce spin
locking, i.e., to freeze the electronic spin, at certain field parameters. We
show how the symmetry of the Hamiltonian determines the quasienergy spectrum
which presents degeneracies at certain field parameters, and how it is
reflected in the charge and spin dynamics.
