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Stacking structure and superconductivity in ruthenium-iridium bicrystal superlattices

1986; American Physical Society; Volume: 34; Issue: 3 Linguagem: Inglês

10.1103/physrevb.34.2022

1095-3795

Roy Clarke, F. J. Lamelas, Ctirad Uher, C. P. Flynn, J. E. Cunningham,

Rare-earth and actinide compounds

The stacking structure and epitaxial ordering are studied in molecular-beam-epitaxy-grown Ru-Ir superlattices of wavelengths $\ensuremath{\lambda}=10, 41, \mathrm{and} 62$ \AA{}. These samples span the fcc-hcp crossover previously found to occur when the Ir component is thinner than about 10 monolayers. Evidence for a new stacking sequence of period $3\ensuremath{\lambda}$ is found in the $\ensuremath{\lambda}=41$ \AA{} sample, possibly resulting from stacking faults in the Ir layers. The superconducting transition temperature is significantly higher in the 41-\AA{} sample (${T}_{c}=0.19$ K) than in the 62-\AA{} sample (${T}_{c}=0.15$ K), whereas the 10-\AA{} sample is not superconducting down to 20 mK.