| Budget Amount *help |
¥4,190,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
Magnetic properties of double perovskites Ca_2LnRuO_6 (Ln = Y, La-Lu) were investigated. From the magnetic susceptibility and specific heat measurements, it is found that all these compounds show an antiferromagnetic transition (T_N = 10-34K), and that the antiferromagnetic ordering of Ru^<+5> ions occurs below these temperatures. In these compounds, the larger Ln ions tend to occupy the A site of the perovskite ABO_3, while the smaller Ln ions tend to occupy the B site. The Nd ions in Ca_2NdRuO_6 are situated at the A site and show an antiferromagnetic transition at 1.6 K, which is much lower than T_N = 11.5 K. On the other hand, the Yb ions in Ca_2YbRuO_6 are situated at the B site, and a long-range antiferromagnetic ordering due to both Yb^<3+> and Ru^<5+> ions occurs at 34 K. The magnetic structure of Ca_2YbRuO_6 was determined by powder neutron diffraction measurements.
In addition, ternary potassium rare earth oxides KLnO_2 (Ln = Y, Nd, Sm-Lu) have been determined by powder X-ray diffraction using the Rietveld analysis method. All of the KLnO_2 compounds have the same hexagonal a-NaFeO_2 structure. Magnetic susceptibility measurements for these compounds show paramagnetic behavior down to 1.8 K. The specific heat measurements indicate that the Gd, Dy, Ho and Er compounds have a magnetic anomaly at 1.1, 1.8, 1.2 and 0.8 K, respectively.
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