Unconventional superconductivity in Ba(0.6)K(0.4)Fe2As2 from inelastic neutron scattering

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Iron arsenide superconductors display high transition temperatures (T(c) > 50 K), drawing parallels with copper oxide superconductors.
• Superconductivity in both material classes emerges upon suppression of antiferromagnetic order via chemical doping.
• A characteristic magnetic resonance exists in copper oxide superconductors, linked to an unconventional superconducting energy gap symmetry.

Purpose of the Study:

• To investigate the symmetry of the superconducting energy gap in iron arsenide superconductors.
• To determine if iron arsenides share the unconventional gap symmetry observed in copper oxides.
• To provide phase-sensitive evidence for the nature of superconductivity in iron arsenides.

Main Methods:

• Inelastic neutron scattering experiments were conducted on Ba(0.6)K(0.4)Fe(2)As(2).
• Measurements were performed below the superconducting transition temperature (T(c)).
• The study focused on observing magnetic excitations within the superconducting phase.

Main Results:

• A magnetic resonance was observed below T(c) in Ba(0.6)K(0.4)Fe(2)As(2).
• This resonance is indicative of an unconventional superconducting energy gap symmetry.
• The findings provide phase-sensitive evidence for this gap symmetry.

Conclusions:

• Iron arsenide superconductors possess an unconventional superconducting energy gap symmetry.
• This symmetry is analogous to that found in copper oxide superconductors.
• The observed magnetic resonance confirms the unique electronic pairing interactions in iron arsenides.