Spin resonance in the d-wave superconductor CeCoIn5

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• CeCoIn5 is a heavy fermion superconductor with a critical temperature (Tc) of 2.3 K.
• Antiferromagnetic spin fluctuations are present in the normal state of CeCoIn5.
• Understanding the interplay between magnetism and superconductivity is crucial for heavy fermion systems.

Purpose of the Study:

• To investigate the nature of antiferromagnetic spin fluctuations in CeCoIn5 using neutron scattering.
• To explore the evolution of these fluctuations in the superconducting state.
• To determine the relationship between magnetism and the d-wave superconducting order parameter.

Main Methods:

• Neutron scattering experiments were performed on CeCoIn5.
• Analysis focused on probing spin fluctuations at various energy and momentum transfers.
• Comparison with related materials like CeIn3 and CeRhIn5 was made.

Main Results:

• Slow, commensurate antiferromagnetic spin fluctuations (energy scale Gamma ≈ 0.3 meV) with isotropic correlations were observed.
• A sharp spin resonance (energy scale Gamma < 0.07 meV) at ω ≈ 0.60 meV developed below Tc.
• This resonance removed spectral weight at low energy transfers.

Conclusions:

• The findings indicate strong coupling between f-electron magnetism and superconductivity in CeCoIn5.
• The observed spin resonance is consistent with a d-wave superconducting gap satisfying Δ(q+Q0) = -Δ(q).
• Neutron scattering provides key insights into the magnetic-superconducting interplay in this heavy fermion system.