ANISOTROPY OF THE LATTICE VIBRATION OF EU AND CU IN HIGH-TC SUPERCONDUCTOR BA2EUCU3O7 ANALYZED BY EU-151 AND FE-57 MOSSBAUER-EFFECT

The anisotropy of superconductivity in high Tc superconductors indicates that it is important to clarify the anisotropies of microscopic properties in these materials. In this work, we observed the anisotropy of the lattice vibration of Eu and Cu in Ba2EuCu3O7 by Eu-151 and Fe-57 Mossbauer effect. The c-axis aligned samples were prepared by healing the mixture of epoxy and Ba2EuCu3O7 powder in a magnetic field. For Fe-57 Mossbauer measurement the sample doped with Fe-57, Ba2Eu(Cu0.99Fe0.01)3O7, was used. The temperature dependence of Mossbauer spectrum was measured in two cases, c-axis parallel-to gamma-ray and c-axis perpendicular-to gamma-ray. The Debye temperature of Eu along c-axis (230 K) was lower than that in ab-plane (265 K). The Debye temperature of Fe-57 substituted for Cu(2) was lower(378 K) along c-axis than in ab-plane (417 K). the Debye temperature of Fe-57 substituted for Cu(1) having no oxygen atom in a-axis was 435 K along c-axis and 416 K in ab-plane. These results are interpreted by the oxygen configuration around the Mossbauer atoms.