  In a holographic probe-brane model exhibiting a spontaneously spatially
modulated ground state, we introduce explicit sources of symmetry breaking in
the form of ionic and antiferromagnetic lattices. For the first time in a
holographic model, we demonstrate pinning, in which the translational Goldstone
mode is lifted by the introduction of explicit sources of translational
symmetry breaking. The numerically computed optical conductivity fits very well
to a Drude-Lorentz model with a small residual metallicity, precisely matching
analytic formulas for the DC conductivity. We also find an instability of the
striped phase in the presence of a large-amplitude ionic lattice.
