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probed by anisotropic low-energy excitations石原 滉大*; 六本木 雅生*; 小林 雅之*; 今村 薫平*; 水上 雄太*; 酒井 宏典; Opletal, P.; 常盤 欣文; 芳賀 芳範; 橋本 顕一郎*; et al.
Nature Communications (Internet), 14, p.2966_1 - 2966_7, 2023/05
被引用回数：5 パーセンタイル：92.42(Multidisciplinary Sciences)重い電子系超伝導UTeの超伝導対称性を極低温磁場侵入長測定により研究した。異方的な低エネルギー準粒子励起が観測され、多成分カイラル超伝導を強く示唆する。このうち最も実験をよく説明するのは、カイラル非ユニタリー状態である。
by tuning nematicity and magnetism in FeSe
S
superconductors松浦 康平*; 水上 雄太*; 新井 佑基*; 杉村 優一*; 前島 尚行*; 町田 晃彦*; 綿貫 徹*; 福田 竜生; 矢島 健*; 廣井 善二*; et al.
Nature Communications (Internet), 8, p.1143_1 - 1143_6, 2017/10
被引用回数：80 パーセンタイル：91.57(Multidisciplinary Sciences)A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature (). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving nonmagnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe have considerable overlap, how each order affects superconductivity remains perplexing. Here we construct the three-dimensional electronic phase diagram, temperature (
) against pressure (
) and iso-valent S-substitution (
), for FeSeS. By simultaneously tuning chemical and physical pressures, against which the chalcogen height shows a contrasting variation, we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended nonmagnetic tetragonal phase emerges, where shows a striking enhancement. The completed phase diagram uncovers that high- superconductivity lies near both ends of the dome-shaped antiferromagnetic phase, whereas remainslow near the nematic critical point.
Si利根川 翔*; 笠原 成*; 福田 竜生; 杉本 邦久*; 安田 伸広*; 鶴原 悠悟*; 渡邊 大樹*; 水上 雄太*; 芳賀 芳範; 松田 達磨*; et al.
Nature Communications (Internet), 5, p.4188_1 - 4188_7, 2014/06
被引用回数：52 パーセンタイル：89.07(Multidisciplinary Sciences)We report on the observation of lattice symmetry breaking from the fourfold to twofold structure by high-resolution synchrotron X-ray diffraction measurements at zero field. Small orthorhombic symmetry-breaking distortion sets in at the transition temperature with a jump, uncovering the weakly first-order nature of the hidden-order transition. This distortion is observed only in ultra pure samples, implying a highly unusual coupling nature between the electronic pneumaticity and underlying lattice.
(AsP)笠原 成*; Shi, H. J.*; 橋本 顕一郎*; 利根川 翔*; 水上 雄太*; 芝内 孝禎*; 杉本 邦久*; 福田 竜生; 寺嶋 孝仁*; Nevidomskyy, A. H.*; et al.
Nature, 486(7403), p.382 - 385, 2012/06
被引用回数：385 パーセンタイル：99.31(Multidisciplinary Sciences)The electron nematicity, which break rotational symmetry of the crystal lattice, has been recently observed in high- superconductors. In iron-pnictides, it has been associated with the tetragonal-to-orthorhombic structural transition at 
, and the observations has been limited in the orthorhombic phase or in the tetragonal phase under uniaxial strain. In this investigation we provide magnetic torque measurements, a thermodynamic evidence which clearly shows the development of nematicity well above and the persistence in the nonmagnetic superconducting regime. Combined with synchrotron X-ray measurements, our results identify two distinct temperatures-one at 
, signifying a true nematic transition, and the other at (
), which we show to be not a true phase transition, but rather what we refer to as a "meta-nematic transition", in analogy to the well-known metamagnetic transition in the theory of magnetism.
の最適ドープ試料における磁場侵入長測定から見た超伝導ギャップ構造水上 雄太*; 川本 雄太*; Goh, S. K.*; 石角 元志*; 石田 茂之*; 鬼頭 聖*; 伊豫 彰*; 永崎 洋*; 社本 真一; 芝内 孝禎*; et al.
no journal, ,
今回われわれは母物質LaFeAsOにおいて酸素欠損させることにより得られる超伝導体LaFeAsOの最適ドープ試料(T
25K)を用いて、準粒子の低エネルギー励起を直接観測可能な磁場侵入長測定を500mK(T/(T0.02)まで行った。講演では磁場侵入長の温度依存性の詳細を報告し、超伝導ギャップ構造について議論したい。
