Magnetic structure of EuFe₂As₂ determined by single-crystal neutron diffraction

Since magnetism and superconductivity appears to be intimately related in iron pnictides, it is important to understand the magnetic properties. The investigation of the interplay between the lanthanide and iron magnetism may also be crucial for a deeper understanding of the magnetic and electronic properties of iron pnictides. Among parent compounds of iron pnictide superconductors, EuFe₂As₂ stands out due to the presence of both spin density wave of Fe and antiferromagnetic AFM ordering of the localized Eu²⁺ moment.

Single-crystal neutron-diffraction studies were carried out to determine the magnetic structure and to investigate the coupling of two magnetic sublattices. Long-range AFM ordering of Fe and Eu spins was observed below 190 and 19 K, respectively. It takes place at the same temperature as the tetragonal to orthorhombic structural phase transition, which indicates the strong coupling between structural and magnetic components. While both Fe and Eu spins are aligned along the long a axis as experimentally determined, our studies suggest a weak coupling between the Fe and Eu magnetism.

Y. Xiao et al., “Magnetic structure of EuFe₂As₂ determined by single-crystal neutron diffraction”Phys. Rev. B 80, 174424 (2009).

Contact: Yixi Su

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