Novel Anisotropic Superconductivity in Silicides

다국어 초록 (Multilingual Abstract)

The discovery of superconductivity with Tc ∽39 K in MgB2 renewed our interest in intermetalic compounds containing light elements. We have revisited superconductivity in anisotropic silicides, such as CaMSi (M = Al and Ga), R5Ir4Si10 (R: rare-earth elements), and Lu2Fe3Si5. In CaAlSi with the AlB2 structure, an anomalous angular dependence of the upper critical field is found, sugesting the presence of a decoupled superconducting region. An X-ray diffraction study has shown the presence of a pronounced superlatice structure along thec-axis. Magneto-optical observations on the ac-plane of CaAlSi reveal the presence of strong inhomogeneities. Most R5Ir4Si10 (R: Sc, Y, rare-earth elements) compounds show a charge-density wave instability with the ex- ception of Sc5Ir4Si10, which shows the highest Tc among these compounds. We have compared their anisotropic superconductivity in order to get some insight into the exceptional properties of Sc5Ir4Si10. Lu2Fe3Si5 is a superconductor with Tc ∽ 6 K and containing nonmagnetic iron. Previous specific heat measurements show that Lu2Fe3Si5 has a large residual density of state in the superconducting state. We have sucesfuly grown high-quality single crystals of Lu2Fe3Si5 and found a signature of the presence of a second superconducting gap as in MgB2.

참고문헌 (Reference)

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