The magnetic structure of EuCu₂Sb₂

Author： Ryan D H Cadogan J M Anand V K Johnston D C Flacau R

E-ISSN： 1361-648X|27|20|206002-206006

ISSN： 0953-8984

Source： Journal of Physics: Condensed Matter, Vol.27, Iss.20, 2015-05, pp. : 206002-206006

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Abstract

Antiferromagnetic ordering of EuCu₂Sb₂ which forms in the tetragonal CaBe₂Ge₂-type structure (space group P4/nmm #129) has been studied using neutron powder diffraction and ¹⁵¹Eu Mössbauer spectroscopy. The room temperature ¹⁵¹Eu isomer shift of −12.8(1) mm s⁻¹ shows the Eu to be divalent, while the ¹⁵¹Eu hyperfine magnetic field (B_hf) reaches 28.7(2) T at 2.1 K, indicating a full Eu²⁺ magnetic moment. B_hf(T) follows a smooth &$S=frac{7}{2}$ ; Brillouin function and yields an ordering temperature of 5.1(1) K. Refinement of the neutron diffraction data reveals a collinear A-type antiferromagnetic arrangement with the Eu moments perpendicular to the tetragonal c-axis. The refined Eu magnetic moment at 0.4 K is 7.08(15) μ_B which is the full free-ion moment expected for the Eu²⁺ ion with &$S=frac{7}{2}$ ; and a spectroscopic splitting factor of g = 2.