EuPdSn₂: magnetic structures in view of resonant X-ray Bragg diffraction.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Strongly Correlated Electron Systems

Background:

• Materials with divalent europium (Eu²⁺) ions are of significant interest due to their unique magnetic properties and applications.
• The magnetic structure of EuPdSn₂ remains unresolved, with conflicting evidence from neutron diffraction suggesting coexisting ferromagnetic and antiferromagnetic phases.
• Eu²⁺ ions are valuable for substitution in various materials, but their S-state nature simplifies crystal electric field effects.

Purpose of the Study:

• To resolve the ambiguous magnetic structure of EuPdSn₂.
• To explore the potential of single crystal resonant X-ray Bragg diffraction for analyzing complex magnetic structures.
• To investigate the role of axial and polar multipoles in the magnetic properties of EuPdSn₂.

Main Methods:

• Symmetry-informed analytic magnetic structure factors were developed for resonant X-ray Bragg diffraction.
• Europium (Eu) atomic resonances were utilized for X-ray diffraction experiments.
• Analysis was informed by existing neutron diffraction data and specific heat measurements.

Main Results:

• Resonant X-ray diffraction demonstrates significant potential for resolving complex magnetic structures.
• Europium ions occupy Wyckoff positions lacking inversion symmetry in the inferred magnetic space groups.
• Axial and polar Eu multipoles are essential components for both neutron and resonant X-ray diffraction patterns.

Conclusions:

• The proposed antiferromagnetic phase of EuPdSn₂ supports the presence of anapoles (magnetic polar dipoles).
• Resonant X-ray diffraction is a powerful technique for probing magnetic structures, particularly where neutron diffraction is limited.
• Understanding the magnetic multipoles is crucial for characterizing materials with complex magnetic ordering.