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La
Fe
Ni
As
Xie, T.*; Liu, C.*; 梶本 亮一; 池内 和彦*; Li, S.*; Luo, H.*
Journal of Physics; Condensed Matter, 34(47), p.474001_1 - 474001_8, 2022/11
被引用回数：0 パーセンタイル：0(Physics, Condensed Matter)We report time-of-flight inelastic neutron scattering (INS) investigations on the spin fluctuation spectrum in the 112-type iron-based superconductor (FeSC) CaLaFeNiAs (CaLa-112). In comparison to the 122-type FeSCs with a centrosymmetric tetragonal lattice structure (space group 
) at room temperature and an in-plane stripe-type antiferromagnetic (AF) order at low temperature, the 112 system has a noncentrosymmetric structure (space group 
) with additional zigzag arsenic chains between Ca/La layers and a magnetic ground state with similar wavevector 
but different orientations of ordered moments in the parent compounds. Our INS study clearly reveals that the in-plane dispersions and the bandwidth of spin excitations in the superconducting CaLa-112 closely resemble to those in 122 systems. While the total fluctuating moments 
/Fe are larger than 122 system, the dynamic correlation lengths are similar (
). These results suggest that superconductivity in iron arsenides may have a common magnetic origin under similar magnetic exchange couplings with a dual nature from local moments and itinerant electrons, despite their different magnetic patterns and lattice symmetries.
齋藤 慎平*; De Rosis, A.*; Fei, L.*; Luo, K. H.*; 海老原 健一; 金子 暁子*; 阿部 豊*
Physics of Fluids, 33(2), p.023307_1 - 023307_21, 2021/02
被引用回数：22 パーセンタイル：98.29(Mechanics)流れ場で沸騰が発生する現象は強制対流沸騰として知られている。今回、飽和条件の流れ場中の円柱上での沸騰システムを数値的に調査した。複雑な気液相変化現象に対処するために、擬ポテンシャル格子ボルツマン法(LBM)に基づく数値スキームを開発した。高いレイノルズ数の数値安定性を高めるため、衝突項を中心モーメント(CM)の空間で解いた。CMベースのLBMに適した力場スキームを採用することで簡潔でありながら堅牢なアルゴリズムとなっている。さらに、熱力学的一貫性を確保するために必要な追加項をCMの枠組みにおいて導出した。現在のスキームの有効性は、核形成,成長、および30-30000の間で変化するレイノルズ数の蒸気泡の離脱を含む一連の沸騰プロセスに対してテストされた。開発したCMベースのLBMは、初期気相などの人工的な入力なしに、核沸騰,遷移沸騰、および膜沸騰の沸騰様式を再現できる。結果からプール沸騰ではなく強制対流システムでも抜山曲線として知られる典型的な沸騰曲線が現れることが分かった。また、今回のシミュレーションは膜沸騰領域でも断続的な直接固液接触の実験的観察を支持することが分かった。
AsXie, T.*; Wei, Y.*; Gong, D.*; Fennell, T.*; Stuhr, U.*; 梶本 亮一; 池内 和彦*; Li, S.*; Hu, J.*; Luo, H.*
Physical Review Letters, 120(26), p.267003_1 - 267003_7, 2018/06
被引用回数：28 パーセンタイル：84.8(Physics, Multidisciplinary)We report an inelastic neutron scattering study on the spin resonance in the bilayer iron-based superconductor CaKFe
As. In contrast to its quasi-two-dimensional electron structure, three strongly 
-dependent modes of spin resonance are found below 
= 35 K. The mode energies are below and linearly scale with the total superconducting gaps summed on the nesting hole and electron pockets, essentially in agreement with the results in cuprate and heavy fermion superconductors. This observation supports the sign-reversed Cooper-pairing mechanism under multiple pairing channels and resolves the long-standing puzzles concerning the broadening and dispersive spin resonance peak in iron pnictides. More importantly, the triple resonant modes can be classified into odd and even symmetries with respect to the distance of Fe-Fe planes within the Fe-As bilayer unit. Thus, our results closely resemble those in the bilayer cuprates with nondegenerate spin excitations, suggesting that these two high- superconducting families share a common nature.
(As
P
) superconductorHu, D.*; Yin, Z.*; Zhang, W.*; Ewings, R. A.*; 池内 和彦*; 中村 充孝; Roessli, B.*; Wei, Y.*; Zhao, L.*; Chen, G.*; et al.
Physical Review B, 94(9), p.094504_1 - 094504_7, 2016/09
被引用回数：15 パーセンタイル：60.38(Materials Science, Multidisciplinary)最適Pドープされた超伝導体BaFe(AsP) (T
=30K)におけるスピン励起の温度及びエネルギー依存性が非弾性中性子散乱実験を使って調べられた。我々の実験結果は密度汎関数理論や動的平均場理論で予想される計算結果と矛盾しておらず、BaFe(AsP)における平均プニクトゲン高さの減少が、電子相関の強さを弱め、磁気励起の有効バンド幅の増加に寄与することを示唆している。
Li, B.; Luo, X. H.*; Wang, H.*; Ren, W. J.*; Yano, S.*; Wang, C.-W.*; Gardner, J. S.*; Liss, K.-D.*; Miao, P.*; Lee, S.-H.*; et al.
Physical Review B, 93(22), p.224405_1 - 224405_6, 2016/06
被引用回数：43 パーセンタイル：86.13(Materials Science, Multidisciplinary)Competition between ferromagnetic and antiferromagnetic phases on frustrated lattices in hexagonal Laves phase compound Hf
Ta
Fe is investigated by using neutron diffraction as a function of temperature and magnetic fields and density-functional-theory calculations. At 325 K, the compound orders into the 120
frustrated antiferromagnetic state with well-reduced magnetic moment and an in-plane lattice contraction simultaneously sets in. With further cooling down, however, the accumulated distortion in turn destabilizes this susceptible frustrated structure. The frustration is completely relieved at 255 K when the first-order transition to the ferromagnetic state takes place, where a colossal negative volumetric thermal expansion, 
/K, is obtained. Meanwhile, the antiferromagnetic state can be suppressed by few Tesla magnetic fields, which results in a colossal positive magnetostriction. Such delicate competition is attributed to the giant magnetic fluctuation inherent in the frustrated antiferromagnetic state. Therefore, the magnetoelastic instability is approached even under a small perturbation.
Ding, F.*; Luo, G.-N.*; Pitts, R.*; Litnovsky, A.*; Gong, X.*; Ding, R.*; Mao, H.*; Zhou, H.*; Wampler, W. R.*; Stangeby, P. C.*; et al.
Journal of Nuclear Materials, 455(1-3), p.710 - 716, 2014/12
被引用回数：24 パーセンタイル：88.67(Materials Science, Multidisciplinary)A movable material probe system (Material and Plasma Evaluation System: MAPES) with an independent pumping system and a sample exchange chamber has been developed and installed on a horizontal port of the EAST tokamak for studies of plasma material interaction (PMI). In the 2012 experimental campaign, deposition and erosion were studied for three samples: mock-up of the outer first wall panels (FWPs) in ITER, castellated tungsten, and molybdenum mirrors. The FWPs with carbon deposition layer were exposed to helium plasmas. The maximum erosion rate of the carbon was valuated to be 8 nm/s. The castellated tungsten with rectangular cells and roof-like shaped cells was exposed to deuterium plasmas to compare amount of deposits on the gap surface. The amount of carbon and boron impurities on the gap surface of the roof-like shaped cells were reduced to less than 30% compared with that of the rectangular cells. The molybdenum mirrors of which protective ducts are installed in front were exposed to deuterium plasmas in order to investigate effects of length of the ducts. It was found that the reflectivity of the mirrors with 60 mm-long protective ducts is kept the initial reflectivity.
Hellgren, N.*; Guo, J.*; Luo, Y.*; S
the, C.*; 安居院 あかね; Kashtanov, S.*; Nordgren, J.*; gren, H.*; Sundgren, J.-E.*
Thin Solid Films, 471(1-2), p.19 - 34, 2005/01
被引用回数：129 パーセンタイル：96.54(Materials Science, Multidisciplinary)窒化炭素は近年ハードディスクや記録ヘッドなどの材料として着目されている。本研究ではマグネトスパッタ法によって作成した窒化炭素薄膜の電子構造を、軟X線光電子分光,X線吸収分光法,発光分光法によって測定した。これにより、薄膜作成時の温度などの条件で窒素-炭素の結合や、そのマイクロストラクチャーが変化することがわかった。
Ding, F.*; 芦川 直子*; 福本 正勝; 片山 一成*; Mao, H.*; Ding, R.*; Xu, Q.*; Wu, J.*; Xie, C. Y.*; Luo, G.-N.*
no journal, ,
Castellated tungsten samples with different gap width and gap depth are exposed to the scrape-off-layer plasma with the material and plasma evaluation system (MAPES) to investigate effects of castellation configurations on impurity deposition and fuel retention. After the plasma exposure, composition and distribution of the impurity deposited on the inner surface of the gap are investigated. The composition and the distribution of the deposits have a strong dependence of the gap configuration. The amount of the deposits on the inner surface of the inverse trapezoid gap is small compared with that of the rectangular gap with the same top width. For all the samples, the amount of the deposits decreases with the gap width and depth.
