Reentrant hidden order at a metamagnetic quantum critical end point.

Magnetization measurements of URu2Si2 in pulsed magnetic fields of 44 T reveal that the hidden order phase is destroyed before appearing in the form of a reentrant phase between approximately 36 and 39 T. Evidence for conventional itinerant electron metamagnetism at higher temperatures suggests that the reentrant phase is created in the vicinity of a quantum critical end point.