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花栗 哲郎*; 幸坂 祐生*; Davis, J. C.*; Lupien, C.*; 山田 幾也*; 東 正樹*; 高野 幹夫*; 大石 一城; 小野 雅紀*; 高木 英典*
Nature Physics, 3(12), p.865 - 871, 2007/12
被引用回数:148 パーセンタイル:95.60(Physics, Multidisciplinary)High-transition-temperature (high-) superconductivity is ubiquitous in the cuprates containing CuO
planes, but each cuprate has its own character. The study of the material dependence of the
-wave superconducting gap (SG) should provide important insights into the mechanism of high-
superconductivity. However, because of the "pseudogap" phenomenon, it is often unclear whether the energy gaps observed by spectroscopic techniques really represent the SG. Here, we use scanning tunnelling spectroscopy to image nearly optimally doped Ca
Na
CuO
Cl
(Na-CCOC) with
K. It enables us to observe the quasiparticle interference effect in this material, through which we obtain unambiguous information on the SG. Our analysis of quasiparticle interference in Na-CCOC reveals that the SG dispersion near the gap node is almost identical to that of Bi
Sr
CaCu
O
(Bi2212) at the same doping level, despite the
of Bi2212 being three times higher than that of Na-CCOC. We also find that the SG in Na-CCOC is confined in narrower energy and momentum ranges than Bi2212, which explains
at least in part
the remarkable material dependence of
.
花栗 哲郎*; 幸坂 祐生*; Davis, J. C.*; Lupien, C.*; 山田 幾也*; 東 正樹*; 高野 幹夫*; 大石 一城; 高木 英典*
Physica C, 460-462, p.954 - 955, 2007/09
被引用回数:2 パーセンタイル:6.30(Physics, Applied)高分解能走査型トンネル顕微鏡により最適ドープのCaNa
CuO
Cl
の研究を行った。以前低ドープの試料で見られていた「チェッカーボード」と呼ばれる局所状態密度の変調がここでも見られた。また、空間的に不均一なギャップが見られ、このギャップは昇温とともに消失する傾向にあった。これらの結果はギャップチェッカーボード型変調と共存した超伝導に関係していることを示唆する。