Within the time-dependent Gutzwiller approximation for the Hubbard model we
compute the magnetic fluctuations of vertical metallic stripes with parameters
appropriate for La1.875βBa0.125βCuO4β (LBCO). For bond- and
site-centered stripes the excitation spectra are similar, consisting of a
low-energy incommensurate acoustic branch which merges into a ``resonance
peak'' at the antiferromagnetic wave vector and several high-energy optical
branches. The acoustic branch is similar to the result of theories assuming
localized spins whereas the optical branches are significantly different.
Results are in good agreement with a recent inelastic neutron study of LBCO.Comment: 4 pages, 2 eps figure