EuFe2(As(1-x)P(x))2: reentrant spin glass and superconductivity.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism and Superconductivity

Background:

• Investigating the interplay between magnetism and superconductivity is crucial for understanding complex electronic phases.
• EuFe(2)(As(1-x)P(x))(2) is a promising material system for exploring such phenomena due to the presence of Eu(2+) magnetism.

Purpose of the Study:

• To systematically investigate the magnetic, transport, and thermodynamic properties of EuFe(2)(As(1-x)P(x))(2) single crystals.
• To explore the complex interplay between Eu(2+) magnetism and superconductivity across the entire substitution range (0≤x≤1).

Main Methods:

• Synthesis of single crystals of EuFe(2)(As(1-x)P(x))(2) for 0≤x≤1.
• Systematic measurements of magnetic, transport, and thermodynamic properties.
• Analysis of magnetic transitions and their coexistence with superconducting properties.

Main Results:

• Two distinct magnetic transitions were observed below 30 K for all P-substituted crystals, necessitating a revised phase diagram.
• A canted A-type antiferromagnetic order of Eu(2+) at ~20 K and a spin glass transition at lower temperatures were identified.
• Remarkably, a reentrant spin glass state was found to coexist with superconductivity around x≈0.2.

Conclusions:

• The study revises the phase diagram of EuFe(2)(As(1-x)P(x))(2) by revealing new magnetic transitions.
• The coexistence of superconductivity with a reentrant spin glass state in this system presents a novel finding.
• These results offer critical insights into the complex interplay between magnetism and superconductivity in correlated electron systems.