Exchange interaction for the triplet superconductor UTe₂.

Area of Science:

• Condensed Matter Physics
• Quantum Materials

Background:

• Uranium ditelluride (UTe2) exhibits unconventional triplet superconductivity, challenging established theories linking ferromagnetism and superconductivity.
• Understanding the fundamental mechanisms behind UTe2's unique superconducting properties is crucial for advancing the field.

Purpose of the Study:

• To develop a theoretical framework explaining the spin-triplet superconductivity in UTe2.
• To investigate the formation of Cooper pairs in UTe2 through a two-particle exchange interaction.
• To predict and validate the superconducting properties of UTe2 under pressure.

Main Methods:

• Constructing a two-particle exchange interaction model favoring Cooper pair formation in a spin-triplet state.
• Applying a modified Bardeen-Cooper-Schrieffer (BCS) theory.
• Utilizing parameters from ab-initio density functional calculations for electrons and phonons.

Main Results:

• Derived a critical temperature (Tc) of 1.64 K and an average superconducting gap of 0.25 meV at 0 K.
• The theoretical model successfully explains the formation of Cooper pairs in UTe2.
• Predicted changes in Tc and the superconducting gap under pressure, aligning with experimental observations.

Conclusions:

• The proposed theoretical model provides a viable explanation for the unconventional superconductivity in UTe2.
• The study highlights the importance of electron-phonon interactions and ab-initio calculations in understanding complex superconductors.
• The findings offer insights into the behavior of UTe2 under varying pressures, crucial for future material design.