Moessbauer studies and magnetic properties of Ln2SrCu2O6 compounds

Moessbauer and magnetic susceptibility measurements were used to study the magnetic properties of Ln1.9Sr1.1Cu2O6 (Ln = Pr,Nd) and La2SrCu2O6 materials. These compounds were prepared by solid-state reaction and crystallize in a tetragonal structure, space group I4/mmm with two formula units per unit cell. There is only one crystallographic site for Cu atoms, which form a double layer of CuO5 pyramids. These compounds are not superconducting, but we show, using Moessbauer spectroscopy (MS) on iron doped samples and susceptibility measurements, that the Cu planes order antiferromagnetically. The hyperfine fields on iron nuclei at 4.2 K extend from 472 kOe for La2SrCu2O6 to 501 kOe for Nd1.9Sr1.1Cu2O6. The ordering temperatures TN are: ∼20, 190, and 250 K for Ln = La, Pr and Nd, respectively. (orig.)