Phase diagram and annealing effect for Fe1+δTe1-xSx single crystals

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Chemistry

Background:

• Excess iron atoms in Fe(Te, Se, S) crystals complicate the antiferromagnetic ground state and suppress superconductivity.
• Discrepancies exist in the phase diagrams of iron-based superconductors due to intrinsic material complexities.

Purpose of the Study:

• To synthesize Fe1+δTe1-xSx single crystals.
• To establish a phase diagram for the Fe1+δTe1-xSx system with reduced excess iron.
• To investigate the interplay between antiferromagnetism and superconductivity.

Main Methods:

• Synthesis of Fe1+δTe1-xSx single crystals using a melting method.
• Air annealing to partially remove excess iron atoms and improve superconductivity.
• Resistivity and magnetic susceptibility measurements for phase diagram determination.

Main Results:

• Successfully synthesized Fe1+δTe1-xSx single crystals (0 ≤ x ≤ 0.12).
• Air annealing significantly enhanced superconductivity by reducing excess iron.
• A phase diagram was established, revealing a coexisting region of antiferromagnetism and bulk superconductivity (0.07 ≤ x ≤ 0.11).

Conclusions:

• The established phase diagram for Fe1+δTe1-xSx provides new insights into iron-based superconductors.
• The coexistence of antiferromagnetism and superconductivity highlights a common feature across different iron-based superconducting systems.
• The findings suggest similarities between the Fe1+δTe1-xSx system and doped BaFe2As2 and Fe(Te, Se) systems.