Crystal structure and magnetic properties of (Ru0.5Cu0.5)(Sr1.47Ba0.2R<su b>0.33)(R1.34Ce0.66)Cu2Oz (R = Nd, Eu)

초록

The crystal structure and the superconducting and magnetic properties of (Ru0.5Cu0.5)(Sr-1.47- Ba0.2R0.33)(R1.34Ce0.66)Cu2O (z) with R = Nd and Eu samples have been investigated by using X-ray powder diffraction techniques and by using resistivity and magnetization measurements. The Rietveld refinement of the X-ray diffraction data showed that the rotation angle of the Ru octahedron around the c-axis for the R = Nd sample was higher than that of the R = Eu sample. The heat treatment of the R = Nd sample under a N-2 atmosphere led to an increase in the rotation angle, in contrast to the decrease in the rotation angle for the R = Eu sample. The dc magnetic susceptibility measurements for the R = Eu sample after the N-2 treatment showed weak ferromagnetic behavior at temperatures below about 80 K whereas the N-2-treated R = Nd sample exhibited paramagnetic behavior. The experimental results are discussed in connection with local structural changes in the samples.

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