Dynamic competition between spin-density wave order and superconductivity in underdoped Ba(1-x)K(x)Fe2As2

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Unconventional superconductivity often emerges near competing electronic phases.
• Iron pnictides exhibit competing tetragonal-to-orthorhombic structural and spin-density wave (SDW) transitions near superconductivity.
• Macroscopic evidence suggests competition, with suppressed orthorhombicity and magnetic moments in superconducting states.

Purpose of the Study:

• To spectroscopically investigate the coexistence and competition between superconductivity, SDW order, and electronic nematicity in iron pnictides.
• To provide direct evidence for the dynamic interplay of these phases at the electronic level.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES) was performed on detwinned, underdoped Ba(1-x)K(x)Fe2As2 samples.
• ARPES allowed for the visualization of electronic band structures and energy gaps.

Main Results:

• Direct observation of the coexistence of both a spin-density wave (SDW) gap and a superconducting gap within the same electronic structure.
• Following the onset of superconductivity, a decrease in the magnitude of the SDW gap was detected.
• The SDW gap's shift indicated a reduction in orbital anisotropy, consistent with nematic order suppression.

Conclusions:

• The study provides direct spectroscopic evidence for the dynamic competition between superconductivity, SDW order, and electronic nematicity in iron pnictides.
• Suppression of competing orders is crucial for the emergence and behavior of superconductivity in these materials.