High-field superconducting halo in UTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• UTe₂ is a heavy fermion material and a prime candidate for topological superconductivity.
• It exhibits multiple superconducting phases that are induced by magnetic fields.
• One unusual phase emerges only at very high magnetic fields (> 40 tesla) near its low critical temperature (2 K).

Purpose of the Study:

• To investigate the structure and field dependence of the high-field superconducting phase in UTe₂.
• To explore the role of magnetic field orientation in stabilizing this exotic superconducting state.
• To gain insights into the underlying pairing mechanism and order parameter symmetry.

Main Methods:

• Performed magnetic susceptibility measurements on UTe₂ single crystals.
• Applied ultra-high magnetic fields exceeding 40 tesla.
• Systematically varied the magnetic field orientation relative to the crystallographic axes, particularly away from the bc plane.

Main Results:

• The high-field superconducting phase exhibits a distinct halo-like structure around the b crystallographic axis.
• This phase is stabilized by a magnetic field component oriented perpendicular to the material's magnetic easy axis.
• The observed angular dependence strongly suggests a multicomponent spin-triplet order parameter with finite angular momentum Cooper pairs.

Conclusions:

• The findings reveal the intricate structure of a novel high-field superconducting phase in UTe₂.
• The results point towards a complex, likely unconventional, pairing mechanism that challenges existing theories of field-enhanced superconductivity.
• UTe₂'s unique magnetophilic superconducting properties warrant further theoretical and experimental investigation.