Field Induced Multiple Superconducting Phases in UTe_{2} along Hard Magnetic Axis

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Uranium ditelluride (UTe2) exhibits complex superconducting properties.
• Understanding its phase diagram under magnetic fields is crucial for fundamental physics.

Purpose of the Study:

• To investigate the superconducting phase diagram of UTe2 under magnetic fields along the b axis.
• To characterize the low- and high-field superconducting phases and their field-angular dependence.

Main Methods:

• Utilized high-quality single crystals of UTe2.
• Performed simultaneous electrical resistivity and ac magnetic susceptibility measurements.
• Applied magnetic fields along the hard magnetic b axis.

Main Results:

• Identified distinct low-field superconducting (LFSC) and high-field superconducting (HFSC) phases.
• Observed that crystal quality enhances the upper critical field of the LFSC phase.
• Determined a consistent H* of ~15 T for the onset of the HFSC phase, irrespective of crystal quality.
• Detected an intermediate SC phase within the LFSC phase near H*, marked by weak flux pinning.

Conclusions:

• The superconducting phase diagram of UTe2 is sensitive to magnetic fields and crystal quality.
• The critical field H* is an intrinsic property of UTe2, signaling the emergence of the HFSC phase.
• The intermediate SC phase suggests complex vortex dynamics or novel superconducting states in UTe2.