Incommensurate Antiferromagnetism in UTe 2 under Pressure

The discovery of multiple superconducting phases in UTe 2 boosted research on correlated-electron physics. This heavy-fermion paramagnet was rapidly identified as a reference compound to study the interplay between magnetism and unconventional superconductivity with multiple degrees of freedom. The proximity to a ferromagnetic quantum phase transition was initially proposed as a driving force to triplet-pairing superconductivity. However, we find here that long-range incommensurate antiferromagnetic order is established under pressure. The propagation vector k m = ( 0.07 , 0.33 , 1 ) of the antiferromagnetic phase is close to a wave vector where antiferromagnetic fluctuations have previously been observed at ambient pressure. These elements support that UTe 2 is a nearly antiferromagnet at ambient pressure. Our work appeals for theories modeling the evolution of the magnetic interactions and electronic properties, driving a correlated paramagnetic regime at ambient pressure to a long-range antiferromagnetic order under pressure. A deeper understanding of itinerant- f -electron magnetism in UTe 2 will be a key for describing its unconventional superconducting phases.