Structure and magnetic properties of double perovskites SrCaLnRuO6 (Ln = La, Pr, Nd)

摘要

Double perovskite compounds SrCaLnRuO6 (Ln = La, Pr, Nd) were prepared as a single phase. X-ray diffraction measurements show that Ca2+ and Ln3+ ions are partially disordered at the A site and half of the B site of the perovskite ABO3, and that Ca2+/Ln3+ and Ru5+ ions are regularly ordered at the B site. These compounds should be represented by SrCa_(1-x)Ln_x[Ln_(1-x)Ca_x]RuO6 and x = 0.83-0.93 for Ln = La, Pr, and Nd. Magnetic and specific heat measurements show that any of these compounds orders antiferromagnetically at 10-12 K, which is due to the magnetic interactions between Ru5+ ions. The analysis of the magnetic entropy change indicates that the ground states of Ru5+ and Ln3+ ions are both doublet.