Magnetically driven suppression of nematic order in an iron-based superconductor

Area of Science:

• Condensed matter physics
• Materials science
• Solid-state chemistry

Background:

• Superconductivity in iron-based materials is linked to the suppression of stripe spin density wave (SDW) order.
• Nematic order often precedes SDW order, but its origin in these compounds remains unclear.
• Two main theories propose either orbital ordering or magnetic interactions as the driver of nematicity.

Purpose of the Study:

• To investigate the origin of nematic order in iron-based superconductors.
• To explore the relationship between nematic order, spin density wave (SDW) order, and superconductivity.
• To identify new phases in the normal state phase diagram of iron-based materials.

Main Methods:

• Neutron powder diffraction was employed to probe the magnetic and structural properties.
• The study focused on the Ba1-xNaxFe2As2 material system.
• Analysis involved observing phase transitions near the suppression of SDW order.

Main Results:

• An additional fourfold-symmetric phase was observed in Ba1-xNaxFe2As2.
• This phase appears near the suppression of stripe spin density wave (SDW) order.
• The observed phase aligns with predictions from magnetically driven models of nematic order.

Conclusions:

• The discovery provides evidence supporting magnetically driven mechanisms for nematic order in iron-based superconductors.
• Understanding this new phase is crucial for developing a comprehensive theory of superconductivity in these materials.
• Further research into the interplay of magnetic interactions, nematicity, and superconductivity is warranted.