  We study spin-resolved resonant tunneling in a system of two quantum dots
sandwiched between doped quantum wells. In the coherent (Dicke) regime, i.e.,
when quantum dot separation is smaller than the Fermi wavelength in a
two-dimensional electron gas in quantum wells, application of an in-plane
magnetic field leads to a pronounced spin-resolved structure of the conductance
peak lineshape even for very small Zeeman splitting of the quantum dots'
resonant levels. In the presence of electron-gas spin-orbit coupling, this
spin-resolved structure gets washed out due to Fermi surface deformation in the
momentum space. We also show that Aharonov-Bohm flux penetrating the area
enclosed by electron tunneling pathways completely destroys conductance spin
structure.
