Figure 4: Temperature–magnetic field and temperature–pressure phase diagrams of URu₂Si₂.

PM, CPM and PPM are the high-temperature, the low-temperature correlated and the high-field polarized paramagnetic regimes, respectively, HO and SC the hidden-order and superconducting phases, respectively, AF the antiferromagnetic state, and SDW the spin-density-wave state. For the AF, SDW and PPM regimes, a sketch of the magnetic structure is shown, where the spheres correspond to the U ions and the arrows represent their magnetic moments. For clarity, a single-component (wavevector k₁=(0.6 0 0)) sine modulation is shown for the SDW, which is suspected to be multi-k. Data points in the phase diagram have been compiled from refs 19, 22, 23, 31, 50.