William Knafo, LNCMI-Toulouse, Shingo Araki, Okayama University, and Daniel Braithwaite, CEA-Grenoble.
The mystery of the hidden-order (HO) phase in the correlated electron paramagnet URu2Si2 is still unsolved. To address this problem, one strategy is to search for clues in the subtle competition between this state and neighboring magnetically ordered states. It is now well established that long-range antiferromagnetic order can be stabilized in this metal when it is under pressure and that a spin density wave manifests itself when a magnetic field is applied along the easy magnetic axis c. However, the complete boundaries of the HO phase in the pressure-magnetic-field plane of the phase diagram have not been determined so far. In this work, we have extracted the three-dimensional magnetic-field-pressure-temperature phase diagram of URu2Si2. Its magnetoresistivity was measured in magnetic fields up to 60 T combined with pressures up to 4 GPa. We find a rich phase diagram indicating a subtle competition between the different types of electronic interactions. The main features are the disappearance of the field-induced spin-density-wave phase and a squeezing out of the HO phase under high pressure. We emphasize that many of the boundaries of the 3D phase diagram are controlled by the field and pressure dependences of a single parameter characterizing the electronic correlations. This gives new constraints for theories that model the electronic correlations and ordered phases in URu2Si2.
Figure: (a) Low-temperature electrical resistivity versus magnetic field and (b) three-dimensional phase diagram of URu2Si2 under pressure and magnetic field applied along c.
Destabilization of hidden order in URu2Si2under magnetic field and pressure, W. Knafo, S.
Araki, G. Lapertot, D. Aoki, G. Knebel, and D. Braithwaite, Nat. Phys. (2020)