Strong-Coupling Superconductivity in Noncentrosymmetric Superconductor Li_2Pd_3B by Sub-meV Photoemission Spectroscopy(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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Noncentrosymmetric superconductors Li_2Pd_3B and Li_2Pt_3B are studied by high-resolution photoemission spectroscopy. The valence band spectra of Li_2Pd_3B and Li_2Pt_3B are well explained by first-principles band calculations. The sub-meV photoemission result shows that the size of the superconducting gap of Li_2Pd_3B is about 1.1meV at 5.4K with a reduced gap value (2Δ_0/k_BT_c) of about 4.5, which is greater than the Bardeen-Cooper-Schrieffer (BCS) value of 3.52. The obtained superconducting gap can be explained more clearly with an s-wave superconducting gap than with p- and d-wave superconducting gaps. This result indicates that Li_2Pd_3B is a conventional strong-coupling superconductor.
社団法人日本物理学会の論文
2009-03-15