Normal Fermi Surface in the Nodal Superconductor CeCoIn_{5} Revealed via Thermal Conductivity

Area of Science:

• Condensed Matter Physics
• Superconductivity Research
• Quantum Materials

Background:

• Heavy-fermion superconductors like CeCoIn_{5} exhibit complex electronic properties.
• Understanding the interplay between superconductivity and Fermi surface topology is crucial.
• Previous studies hinted at field-angle-dependent phenomena in CeCoIn_{5}.

Purpose of the Study:

• To investigate the origin of observed resonances in the thermal conductivity of CeCoIn_{5} under rotating magnetic fields.
• To elucidate the role of Fermi surface structure in superconducting states.
• To explore the utility of thermal conductivity measurements in probing superconducting materials.

Main Methods:

• Measurement of thermal conductivity in CeCoIn_{5} with a rotating magnetic field.
• Applying heat current along the antinodal direction (J||[100]).
• Comparison with previous experiments using heat current along the nodal direction (J||[110]).
• Density-functional-theory (DFT) model calculations of the electronic density of states.

Main Results:

• A sharp resonance in thermal conductivity was observed at a specific magnetic field angle (Θ≈12°) relative to the heat current.
• This resonance aligns crystallographically with a previously reported resonance, confirming its origin in the Fermi surface structure.
• DFT calculations supported the experimental findings, showing peaks in the density of states corresponding to field orientations.

Conclusions:

• The observed thermal conductivity resonances in CeCoIn_{5} are definitively linked to its Fermi surface structure.
• Uncondensed Landau quasiparticles are proposed as the cause of these resonances.
• Rotating magnetic field thermal conductivity measurements provide a powerful tool to probe the normal regions of the Fermi surface within a superconductor.