  We classify the different phases by the "pole-zero mechanism" for a
holographic fermionic system which contains a dipole coupling with strength $p$
on a Q-lattice background. A complete phase structure in $p$ space can be
depicted in terms of Fermi liquid, non-Fermi liquid, Mott phase and pseudo-gap
phase. In particular, we find that in general the region of the pseudo-gap
phase in $p$ space is suppressed when the Q-lattice background is dual to a
deep insulating phase, while for an anisotropic background, we have an
anisotropic region for the pseudo-gap phase in $p$ space as well. In addition,
we find that the duality between zeros and poles always exists regardless of
whether or not the model is isotropic.
