Plasmons in coupled bilayer structures

We calculate the collective charge density excitation dispersion and spectral weight in bilayer semiconductor structures including effects of interlayer tunneling.The out-of-phase plasmon mode (the “acoustic” plasmon) develops a long wavelength gap in the presence of tunneling with the gap being proportional to the square root (linear power) of the tunneling amplitude in the weak (strong) tunneling limit.The in-phase plasmon mode is qualitatively unaffected by tunneling.The predicted plasmon gap should be a useful tool for studying many-body effects.