  Spin-dependent electronic transport through a quantum dot side-coupled to two
quantum dots and attached to ferromagnetic leads with collinear (parallel and
antiparallel) magnetizations is analyzed theoretically. The intra-dot Coulomb
correlations are taken into account, whereas the inter-dot ones are neglected.
Transport characteristics, i.e. conductance and tunnel magnetoresistance
associated with the magnetization rotation from parallel to antiparallel
configurations, are calculated by the noneqiulibrium Green function technique.
The Green functions are derived by the equation of motion method in the
Hartree-Fock approximation. The conductance spectra are shown to reveal
features similar to the Dicke resonance in atomic physics.
