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Spin fluctuations in the 112-type iron-based superconductor Ca$$_{0.82}$$La$$_{0.18}$$Fe$$_{0.96}$$Ni$$_{0.04}$$As$$_{2}$$

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) Ca$$_{0.82}$$La$$_{0.18}$$Fe$$_{0.96}$$Ni$$_{0.04}$$As$$_{2}$$ (CaLa-112). In comparison to the 122-type FeSCs with a centrosymmetric tetragonal lattice structure (space group $$I4/mmm$$) at room temperature and an in-plane stripe-type antiferromagnetic (AF) order at low temperature, the 112 system has a noncentrosymmetric structure (space group $$P2_1$$) with additional zigzag arsenic chains between Ca/La layers and a magnetic ground state with similar wavevector $$mathbf{Q}_mathrm{AF}$$ 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 $$langle m^2 rangle approx 4.6 pm 0.2$$ $$mu_B^2$$/Fe are larger than 122 system, the dynamic correlation lengths are similar ($$xi approx 10$$ ${AA}$). 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.


Unconventional superconductivity in UTe$$_2$$

青木 大*; Brison, J.-P.*; Flouquet, J.*; 石田 憲二*; Knebel, G.*; 徳永 陽; 柳瀬 陽一*

Journal of Physics; Condensed Matter, 34(24), p.243002_1 - 243002_41, 2022/06

 被引用回数:17 パーセンタイル:94.06(Physics, Condensed Matter)

The novel spin-triplet superconductor candidate UTe$$_2$$ attracted enormous attention. We review key experimental and theoretical progress which has been achieved in different laboratories. UTe$$_2$$ has been expected to be close to a ferromagnetic instability, showing many similarities to the U-based ferromagnetic superconductors, URhGe and UCoGe. The competition between different types of magnetic interactions and the duality between the local and itinerant character of the 5 f Uranium electrons, as well as the shift of the U valence appear as key parameters in the rich phase diagrams discovered recently under extreme conditions like low temperature, high magnetic field, and pressure. We discuss macroscopic and microscopic experiments at low temperature to clarify the normal phase properties at ambient pressure for field applied along the three axis of this orthorhombic structure.


Effect of uranium deficiency on normal and superconducting properties in unconventional superconductor UTe$$_2$$

芳賀 芳範; Opletal, P.; 常盤 欣文; 山本 悦嗣; 徳永 陽; 神戸 振作; 酒井 宏典

Journal of Physics; Condensed Matter, 34(17), p.175601_1 - 175601_7, 2022/04

 被引用回数:5 パーセンタイル:92.43(Physics, Condensed Matter)

Single crystals of the unconventional superconductor UTe$$_2$$ have been grown in various conditions. Superconducting samples are nearly stoichiometric within an experimental error of about 1%, while non-superconducting sample significantly deviates from the ideal composition. The superconducting UTe$$_2$$ showed that the large density of states was partially gapped in the normal state, while the non-superconducting sample is characterized by the relatively large electronic specific heat as reported previously.


Nanoscale structural analysis of Pb(Mg$$_{1/3}$$Nb$$_{2/3}$$)O$$_3$$

米田 安宏; 谷口 博基*; 野口 祐二*

Journal of Physics; Condensed Matter, 33(3), p.035401_1 - 035401_8, 2021/01

放射光高エネルギーX線回折実験を用いて、リラクサーPb(Mg$$_{1/3}$$Nb$$_{2/3}$$)O$$_3$$ (PMN)のナノスケール構造解析を行った。PMNはよく知られたリラクサー強誘電体であるが、平均構造が立方晶構造であることから、強誘電性のミクロ構造を説明するために種々のモデルが提案されてきた。我々は2体相関分布関数法(pair distribution function, PDF)を使って20nmまでの広いレンジの局所構造解析を行った。


Soft X-ray irradiation induced metallization of layered TiNCl

Kataoka, Noriyuki*; Tanaka, Masashi*; Hosoda, Wataru*; Taniguchi, Takumi*; 藤森 伸一; Wakita, Takanori*; Muraoka, Yuji*; Yokoya, Takashi*

Journal of Physics; Condensed Matter, 33(3), p.035501_1 - 035501_6, 2021/01

 被引用回数:3 パーセンタイル:45.08(Physics, Condensed Matter)

We have performed soft X-ray spectroscopy in order to study thephotoirradiation time dependence of the valence band structure and chemicalstates of layered transition metal nitride chloride TiNCl. Under the soft X-ray irradiation, the intensities of the states near the Fermi level ($$E_{rm F}$$)and the Ti$$^{3+}$$ component increased, while the Cl 2$$p$$ intensity decreased. Ti2$$p$$-3$$d$$ resonance photoemission spectroscopy confirmed a distinctive Fermiedge with Ti 3$$d$$ character. These results indicate the photo-inducedmetallization originates from deintercalation due to Cl desorption, and thusprovide a new carrier doping method that controls the conducting propertiesof TiNCl.


Asymmetrically optimized structure in a high-$$T_{rm c}$$ single unit-cell FeSe superconductor

深谷 有喜; Zhou, G.*; Zheng, F.*; Zhang, P.*; Wang, L.*; Xue, Q.-K.*; 社本 真一

Journal of Physics; Condensed Matter, 31(5), p.055701_1 - 055701_6, 2019/02

 被引用回数:4 パーセンタイル:27.59(Physics, Condensed Matter)



Band structures of 4$$f$$ and 5$$f$$ materials studied by angle-resolved photoelectron spectroscopy

藤森 伸一

Journal of Physics; Condensed Matter, 28(15), p.153002_1 - 153002_31, 2016/04

 被引用回数:30 パーセンタイル:39.5(Physics, Condensed Matter)

Recent remarkable progresses in angle resolved photoelectron spectroscopy (ARPES) made it possible to directly observe the band structures of 4$$f$$ and 5$$f$$ materials. In particular, ARPES with various light sources such as laser or high-energy synchrotron radiations shed light on the bulk band structures of strongly-correlated materials with the energy scales from few meV to several eV. The main purpose of the present article is to summarize the behaviors of 4$$f$$ and 5$$f$$ band structures of various rare earth and actinide materials observed by modern ARPES techniques, and understand how they can be described by various theoretical frameworks. For 4$$f$$-electron materials, ARPES studies of CeMIn$$_5$$ and YbRh$$_2$$Si$$_2$$ with various incident photon energies are summarized. For U 5$$f$$ compounds, ARPES studies of UFeGa$$_5$$, UPd$$_3$$, and URu$$_2$$Si$$_2$$ are summarized based on various ARPES studies. The present status of the field as well as possible future directions are discussed.


Theory of spin Hall magnetoresistance (SMR) and related phenomena

Chen, Y.-T.*; 高橋 三郎*; 中山 裕康*; Althammer, M.*; Goennenwein, S. T. B.*; 齊藤 英治; Bauer, G. E. W.*

Journal of Physics; Condensed Matter, 28(10), p.103004_1 - 103004_15, 2016/03

 被引用回数:70 パーセンタイル:61.37(Physics, Condensed Matter)



Phonons of Fe-based superconductor Ca$$_{10}$$Pt$$_4$$As$$_8$$(Fe$$_{1-x}$$Pt$$_x$$As)$$_{10}$$

池内 和彦*; 小林 義明*; 鈴木 一範*; 伊藤 正行*; 梶本 亮一; Bourges, P.*; Christianson, A. D.*; 中村 博樹; 町田 昌彦; 佐藤 正俊*

Journal of Physics; Condensed Matter, 27(46), p.465701_1 - 465701_7, 2015/11

 被引用回数:1 パーセンタイル:5.16(Physics, Condensed Matter)



Effect of magnetic field on positron lifetimes of Fe, Co and Ni

Li, H.; 前川 雅樹; 河裾 厚男; 谷村 直樹*

Journal of Physics; Condensed Matter, 27(24), p.246001_1 - 246001_5, 2015/06

 被引用回数:6 パーセンタイル:29.95(Physics, Condensed Matter)

Positron lifetime spectra of Fe, Co and Ni were measured under magnetic field using a $$^{22}$$Na source. Very small but distinguishable difference of positron lifetime upon magnetic field reversal was observed suggesting the existence of two bulk lifetimes associated with majority and minority spin electrons. Using two spin-dependent Fe bulk lifetimes, the difference Doppler broadening of annihilation radiation spectra between majority and minority spin electrons were also examined. Agreement between experiment and theory indicates that spin-polarized positron annihilation spectroscopy may have potential in investigation of spin-aligned electron momentum distribution.


Longitudinal spin Seebeck effect; From fundamentals to applications

内田 健一*; 石田 真彦*; 吉川 貴史*; 桐原 明宏*; 村上 朝夫*; 齊藤 英治

Journal of Physics; Condensed Matter, 26(34), p.343202_1 - 343202_15, 2014/08

 被引用回数:181 パーセンタイル:84.02(Physics, Condensed Matter)

The spin Seebeck effect refers to the generation of spin voltage as a result of a temperature gradient in ferromagnetic or ferrimagnetic materials. When a conductor is attached to a magnet under a temperature gradient, the thermally generated spin voltage in the magnet injects a spin current into the conductor, which in turn produces electric voltage owing to the spin-orbit interaction. The spin Seebeck effect is of increasing importance in spintronics, since it enables direct generation of a spin current from heat and appears in a variety of magnets ranging from metals and semiconductors to insulators. Recent studies on the spin Seebeck effect have been conducted mainly in paramagnetic metal/ferrimagnetic insulator junction systems in the longitudinal configuration in which a spin current flowing parallel to the temperature gradient is measured. This "longitudinal spin Seebeck effect" (LSSE) has been observed in various sample systems and exclusively established by separating the spin-current contribution from extrinsic artefacts, such as conventional thermoelectric and magnetic proximity effects. The LSSE in insulators also provides a novel and versatile pathway to thermoelectric generation in combination of the inverse spin-Hall effects. In this paper, we review basic experiments on the LSSE and discuss its potential thermoelectric applications with several demonstrations.


Possible method to observe the breathing mode of a magnetic domain wall in the Josephson junction

森 道康; 小椎八重 航*; 挽野 真一*; 前川 禎通

Journal of Physics; Condensed Matter, 26(25), p.255702_1 - 255702_5, 2014/06


 被引用回数:3 パーセンタイル:15.77(Physics, Condensed Matter)

A magnetic domain wall (DW) behaves as a massive particle with elasticity. Sliding and oscillation of the DW have been observed experimentally, whereas vibration of a width in the DW, "breathing mode", has not been measured so far. We theoretically propose how to observe the breathing mode by the Josephson junction having a ferromagnetic layer between superconducting electrodes. The current-voltage ($$I$$-$$V$$) curve is calculated by an equivalent circuit of the resistively shunted junction model. The breathing mode is identified by stepwise structures in the $$I$$-$$V$$ curve, which appear at the voltages $$V$$=$$n(hbar/2e$$)$$omega$$ with the fundamental constant $$hbar/e$$, integer number $$n$$, and the frequency of the breathing mode $$omega$$.


Weak itinerant antiferromagnetism in PuIn$$_3$$ explored using $$^{115}$$In nuclear quadrupole resonance

中堂 博之; Koutroulakis, G.*; 安岡 弘志; Bauer, E. D.*; Tobash, P. H.*; Mitchell, J. N.*; Thompson, J. D.*

Journal of Physics; Condensed Matter, 26(3), p.036001_1 - 036001_5, 2014/01

 被引用回数:5 パーセンタイル:25.36(Physics, Condensed Matter)

PuIn$$_3$$における$$^{115}$$In NQR測定の結果について報告する。$$^{115}$$Inの核スピン$$I$$=9/2に期待される4本のNQR共鳴線のうちの3本の共鳴線を観測した。20Kにおいて、それらの共鳴線は等間隔であり、そこからNQR周波数$$nu_{rm Q}=10.45$$MHzと電場勾配の非対称パラメータの$$eta=0$$が導かれた。14Kにおいて、NQR共鳴線の形状と核スピン緩和率1/$$T_1$$は反強磁性転移により変化を生じる。14K以下において、NQRスペクトルより見積もられた内部交番磁化$$M_{rm Q}(T)$$と1/$$T_1$$の温度依存性はスピン揺らぎのSCR理論によりよく説明される。さらに、$$T_1T$$$$M_{rm Q}(T)/M_{rm Q}(0)$$はSCR理論から予言される通りに比例している。これらの結果はPuIn$$_3$$が弱い反強磁性体、すなわち有限温度において反強磁性波数近傍のスピン揺らぎが物性を支配している証拠である。


Quadrupole effects in tetragonal crystals PrCu$$_2$$Si$$_2$$ and DyCu$$_2$$Si$$_2$$

三本 啓輔*; 後藤 沙織*; 根本 祐一*; 赤津 光洋*; 後藤 輝孝*; Dung, N. D.*; 松田 達磨; 芳賀 芳範; 竹内 徹也*; 杉山 清寛*; et al.

Journal of Physics; Condensed Matter, 25(29), p.296002_1 - 296002_8, 2013/07

 被引用回数:2 パーセンタイル:10.96(Physics, Condensed Matter)

We have investigated quadrupole effects in tetragonal crystals of PrCu$$_2$$Si$$_2$$ and DyCu$$_2$$Si$$_2$$ by means of low-temperature ultrasonic measurements. The elastic constant C$$_{44}$$ of PrCu$$_2$$Si$$_2$$ exhibits pronounced softening below 70 K, which is described in terms of a quadrupole susceptibility for a doublet ground state.


Perpendicular magnetic anisotropy with enhanced orbital moments of Fe adatoms on a topological surface of Bi$$_2$$Se$$_3$$

Ye, M.*; 黒田 健太*; 竹田 幸治; 斎藤 祐児; 岡本 和晃*; Zhu, S.-Y.*; 白井 開渡*; 宮本 幸治*; 有田 将司*; 仲武 昌史*; et al.

Journal of Physics; Condensed Matter, 25(23), p.232201_1 - 232201_5, 2013/06

 被引用回数:12 パーセンタイル:50.73(Physics, Condensed Matter)

トポロジカル絶縁体に磁性元素を入れると絶縁体表面に対して垂直方向に強磁性が発現するという理論研究があり、その実現は新しいスピントロにクス技術への足がかりになるものと期待されている。本研究では、トポロジカル絶縁体Bi$$_2$$Se$$_3$$の表面にFeを蒸着し、その磁性をFe L$$_{2,3}$$吸収端における軟X線磁気円二色性で、電子状態を角度分解光電子分光を用いて調べた。磁気円二色性実験ではFeの膜厚依存性、試料表面に対する角度依存性測定も行った。その結果、いずれのFe膜厚(0.013-0.9ML)においても強磁性発現は確認できなかったものの、試料表面に垂直方向に磁気モーメントが向く強い磁気異方性を持った常磁性状態が確認された。また軌道磁気モーメントがFe膜厚の小さい試料において増大し、スピン磁気モーメントと軌道磁気モーメントの比率が強い膜厚依存性を示すこともわかった。この結果はトポロジカル絶縁体に対する磁性元素の量を調節することにより、磁性及び量子輸送現象を制御できる可能性を示すものである。


Solution softening in magnesium alloys; The Effect of solid solutions on the dislocation core structure and nonbasal slip

都留 智仁; 宇田川 豊; 山口 正剛; 板倉 充洋; 蕪木 英雄; 加治 芳行

Journal of Physics; Condensed Matter, 25(2), p.022202_1 - 022202_5, 2013/01

 被引用回数:53 パーセンタイル:87.07(Physics, Condensed Matter)



Observation of a pressure-induced As-As hybridization associated with a change in the electronic state of Fe in the tetragonal phase of EuFe$$_2$$As$$_2$$

小林 寿夫*; 池田 修悟*; 阪口 友唯*; 依田 芳卓*; 中村 博樹; 町田 昌彦

Journal of Physics; Condensed Matter, 25(2), p.022201_1 - 022201_6, 2013/01

 被引用回数:9 パーセンタイル:42.16(Physics, Condensed Matter)



The Temperature dependence of Cu$$_{2}$$O formation on a Cu(110) surface with an energetic O$$_{2}$$ molecular beam

橋之口 道宏*; 吉越 章隆; 寺岡 有殿; 岡田 美智雄*

Journal of Physics; Condensed Matter, 24(39), p.395007_1 - 395007_8, 2012/10

 被引用回数:5 パーセンタイル:25.1(Physics, Condensed Matter)

We report a study of the surface temperature (Ts) dependence of Cu$$_{2}$$O formation on a Cu(110) surface induced by a hyperthermal O$$_{2}$$ molecular beam (HOMB), using X-ray photoemission spectroscopy in conjunction with synchrotron radiation. From the Ts dependence of the O uptake curves, the direct dissociative adsorption process mainly contributes to the formation of the p(2$$times$$1)-O structure with an O coverage of 0.5 ML for 2.2 eV HOMB incidence. On the other hand, the rate of oxidation at the coverage larger than 0.5 ML, particularly in Cu$$_{2}$$O formation, strongly depends on the Ts. Thicker Cu$$_{2}$$O islands were found in homogeneously at 400 and 500 K, suggesting the dominant role of the migration of Cu atoms in the Cu$$_{2}$$O formations on the Cu(110) surface.


A Theoretical study of the reactivity of Cu$$_{2}$$O(111) surfaces; The Case of NO dissociation

岸 浩史*; Padama, A. A. B.*; Arevalo, R. L.*; Moreno, J. L. V.*; 笠井 秀明*; 谷口 昌司*; 上西 真里*; 田中 裕久*; 西畑 保雄

Journal of Physics; Condensed Matter, 24(26), p.262001_1 - 262001_5, 2012/07

 被引用回数:9 パーセンタイル:39.83(Physics, Condensed Matter)



NO dissociation on Cu(111) and Cu$$_{2}$$O(111) surfaces; A Density functional theory based study

Padama, A. A. B.*; 岸 浩史*; Arevalo, R. L.*; Moreno, J. L. V.*; 笠井 秀明*; 谷口 昌司*; 上西 真里*; 田中 裕久*; 西畑 保雄

Journal of Physics; Condensed Matter, 24(17), p.175005_1 - 175005_6, 2012/05

 被引用回数:37 パーセンタイル:79.36(Physics, Condensed Matter)


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