Dynamic properties in the bilayer quantum Hall ferromagnet

The spectral functions of pseudospin response functions in the bilayer quantum Hall system at nu=1 are investigated numerically, where the pseudospin describes the layer degrees of freedom. In the pseudospin-ferromagnetic phase, the lowest-lying excitation branch is closely connected with the ground state through the fluctuations of pseudospin S-y and S-z, and this pseudospin-wave excitation branch plays a significant role in the tunneling-current properties in the system.