Abstract
Two antiferromagnetic substructures of the pseudo-CE type are revealed by neutron-diffraction studies. Their propagation vectors are k 1=(0,0, 1 2 ) and k 2=( 1 2 ,0, 1 2 ) in the Pnma crystal-structure unit cell. The intensities of the magnetic Bragg peaks are proportional to the squares of a modified Brillouin function for spin 3 2 . Its molecular field parameters depend on the reduced sublattice magnetizations σ as T N(1− eσ 2). The fitting parameters are the Néel temperatures T N1=120 and T N2=123 K, and e 1=0.2, e 2=0.16 showing a weakening of the effective exchange. Below 27 K, an additional increase of the magnetic peak intensities is observed. Below ∼85 K, the magnetic behavior is characteristic for a cluster glass. The uniaxial pressure effect on the DC-magnetization shows a sharp minimum near 120 K and it changes sign near 85 K, implying an alteration of the effective superexchange integral.
Published Version
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