Evidence for multiband superconductivity in the heavy Fermion compound UNi2Al3

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Heavy fermion superconductors exhibit unique electronic properties.
• UNi2Al3 is a known heavy fermion superconductor with a transition temperature (Tc) around 1 K.
• Understanding the interplay between magnetism and superconductivity is crucial.

Purpose of the Study:

• Investigate the superconducting properties of UNi2Al3 epitaxial thin films.
• Explore the influence of magnetic ordering on superconductivity.
• Determine the nature of the superconducting state in UNi2Al3.

Main Methods:

• Epitaxial thin film growth of UNi2Al3.
• Electrical resistivity measurements as a function of temperature and magnetic field.
• Anisotropy measurements of critical current and upper critical field.

Main Results:

• Superconducting transition temperature (Tc) shows current-direction dependence, indicating anisotropic superconducting gaps.
• Magnetic ordering at TN (~5 K) significantly impacts resistivity (R(T)) anisotropically.
• Upper critical field (Hc2(T)) data suggest an unconventional spin-singlet superconducting state.

Conclusions:

• The observed anisotropy in UNi2Al3 is linked to the complex Fermi surface and coupling between magnetic moments and charge carriers.
• UNi2Al3 exhibits an unconventional superconducting mechanism, likely spin-singlet, influenced by nearby magnetic order.