  We use a holographic theory to model and study the competition of four
phases: an antiferromagnetic phase, a superconducting phase, a metallic phase
and a striped phase, using as control parameters temperature and a doping-like
parameter. We analyse the various instabilities and determine the possible
phases. One class of phase diagrams, that we analyse in detail, is similar to
that of high-temperature superconductors as well as other strange metal
materials.
