Jülich Centre for Neutron Science (JCNS)

Quantum Materials and Collective Phenomena (JCNS-2)

Phase Diagram of Eu Magnetic Ordering

This member of the pnictide family shows a broad variety of magnetic and superconducting features. Especially the interplay of the Eu and Fe magnetic sublattices in combination with various Co content requires detailed studies with single crystal neutron diffraction. Using the short wavelengths of HEiDi to overcome the strong Eu neutron absorption in these compounds HEiDi contributed to various studies on this family of compounds.

The ground-state magnetic structure of the Eu²⁺ spins is found to develop from the A-type antiferromagnetic (AFM) order in the parent compound, via the A-type canted AFM structure with some net ferromagnetic (FM) moment component along the crystallographic c direction at intermediate Co doping levels, finally to the pure FM order at relatively high Co doping levels.

The phase diagram of Sn-flux-grown Eu(Fe1−xCox )2As2 single crystals, illustrating the evolution of the magnetic ground state of the Eu2+ spins with Co doping. TC(x) is assumed to vary linearly as TN(x) does.

References:

W. T. Jin, Y. Xiao, Z. Bukowski, Y. Su, S. Nandi, A. P. Sazonov, M. Meven, O. Zaharko, S. Demirdis, K. Nemkovski, K. Schmalzl, L. Tran, Z. Guguchia, E. Feng, Z. Fu, and Th. Brückel, Phase diagram of Eu magnetic ordering in Sn-flux-grown Eu(Fe_1-xCo_x)₂As₂ single crystals, Phys. Rev. B 94, 184513 (2016)