Observation of Vortex Stripes in UTe

In conventional type-II superconductors, quantum vortices determine the magnetic response of the system and tend to form regular lattices. UTe2 is a recently discovered heavy Fermion superconductor exhibiting many anomalous macroscopic behaviors, but whether it has a multicomponent order parameter remains open. Here, we study the vortices of UTe2 by employing scanning superconducting quantum interference device microscopy. While a small out-of-plane magnetic field produces typical isolated vortices, a higher field generates vortex stripe patterns that evolve with the vortex density. The stripes form at different locations and along different directions in the surface plane when the field is along the b or c axis. The behavior is reproduced by our simulation based on an anisotropic two-component order parameter. This study shows that UTe2 has a nontrivial disparity of multiple length scales, placing constraints on the multicomponent superconductivity.