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Skyrmion-generated spinmotive forces in inversion broken ferromagnets

山根 結太*; 家田 淳一

Journal of Magnetism and Magnetic Materials, 491, p.165550_1 - 165550_5, 2019/12

We present an analytical study on the spinmotive force (SMF) generated by translational motion of magnetic skyrmion. A SMF refers to an electrical voltage induced by dynamical magnetic textures, which reflects the spatiotemporal variation of the magnetization. The dynamics of a skyrmion thus can be detected by a SMF measurement, which may play an important role in future skyrmion-based technologies. We find the dependence of the SMF on skyrmion structure (e.g., skyrmion or anti-skyrmion, Neel or Bloch type, and the polarity of the skyrmion core) and Rashba and Dresselhaus spin-orbit couplings (SOCs). To this end, we derive explicit formulae for the spin-dependent electric fields originating from the two SOCs. Our findings offer a comprehensive understanding of the phenomenon and an estimation of the electrical voltage signal associated with a moving skyrmion for a given experiment.


Thick-restart block Lanczos method for large-scale shell-model calculations

清水 則孝*; 水崎 高浩*; 宇都野 穣; 角田 佑介*

Computer Physics Communications, 244, p.372 - 384, 2019/11



Q dependence of magnetic resonance mode on FeTe$$_{0.5}$$Se$$_{0.5}$$ studied by inelastic neutron scattering

石角 元志*; 樹神 克明; 梶本 亮一; 中村 充孝; 稲村 泰弘; 池内 和彦*; Ji, S.*; 新井 正敏*; 社本 真一

Condensed Matter (Internet), 4(3), p.69_1 - 69_10, 2019/09



Sensitivity of charged particle activation analysis for long-lived radioactive nuclide determination

大島 真澄*; 山口 友理恵*; 浅井 雅人; 塚田 和明; 後藤 淳*; 伴場 滋*; Bi, C.*; 森本 隆夫*

Journal of Nuclear Science and Technology, 56(9-10), p.866 - 872, 2019/09

長寿命放射性核種35核種の定量のため、8MeV陽子ビームを用いた荷電粒子放射化分析法の分析感度について調査した。それらの核種に対する核反応断面積はALICE-91コードによって見積もり、核異性体生成比は近傍同位体の値からそれらのスピン・パリティの値を考慮して見積もった。その結果、提案する荷電粒子放射化分析法は$$^{135}$$Cs, $$^{244}$$Pu, $$^{129}$$I, $$^{126}$$Sn, $$^{93}$$Mo, $$^{107}$$Pd, $$^{236}$$U, $$^{248}$$Cm, $$^{237}$$Npなどのいくつかの難測定長寿命核種に対して高い感度を示すことが判った。


Spinmotive force in the out-of-plane direction generated by spin wave excitations in an exchange-coupled bilayer element

Zhou, W.*; 関 剛斎*; 今村 裕志*; 家田 淳一; 高梨 弘毅*

Physical Review B, 100(9), p.094424_1 - 094424_5, 2019/09

The generation of the spinmotive force (SMF) requires the temporal and spatial variations of the magnetic moments. We explore an approach to satisfy this requirement by creating asymmetry in a thin film structure along the out-of-plane direction, through the use of an exchange-coupled $$L$$1$$_{0}$$-FePt / Ni$$_{81}$$Fe$$_{19}$$ bilayer element. As the spin wave is excited by rf magnetic field, a continuous dc voltage signal along the out-of-plane direction of the bilayer element appears. The sign of the voltage signal and its microwave power dependency agree with the theoretical framework of the SMF. The corresponding spin wave modes are revealed by carrying out the micromagnetic simulation. Our results demonstrate the generation of the SMF using a vertically structured element in addition to previously reported in-plane structured devices.


Experimental study of Gamow-Teller transitions via the high-energy-resolution $$^{18}$$O($$^3$$He,$$t$$)$$^{18}$$F reaction; Identification of the low-energy "super" -Gamow-Teller state

藤田 浩彦*; 藤田 佳孝*; 宇都野 穣; 吉田 賢市*; 足立 竜也*; Algora, A.*; Csatl$'o$s, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.

Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09




深谷 有喜

陽電子科学, (13), p.3 - 10, 2019/09



Effect of hydrogen on chemical vapor deposition growth of graphene on Au substrates

寺澤 知潮; 平良 隆信*; 保田 諭; 小幡 誠司*; 斉木 幸一郎*; 朝岡 秀人

Japanese Journal of Applied Physics, 58(SI), p.SIIB17_1 - SIIB17_6, 2019/08



Local structure of functional solids

社本 真一

Journal of the Physical Society of Japan, 88(8), p.081008_1 - 081008_11, 2019/08

The local structure study reveals important aspects of the physical properties, because it is closely related to the electronic structure. Some neutron total scattering results are reviewed to show the local functional properties of solids from optical recording to negative thermal expansion to Mott transition materials.


Novel universality class for the ferromagnetic transition in the low carrier concentration systems UTeS and USeS exhibiting large negative magnetoresistance

立岩 尚之; 芳賀 芳範; 酒井 宏典; 山本 悦嗣

Physical Review B, 100(6), p.064413_1 - 064413_7, 2019/08

少数キャリア系UTeS, USeSの強磁性転移温度近辺における磁化の臨界挙動について研究を行った。自発磁化等の温度依存から、各種臨界指数$$beta$$,$$gamma$$, $$delta$$を決定した。これらの強磁性状態は一軸磁気異方性が大きいことが特徴である。しかし、その臨界現象は三次元イジングのユニバーサリティクラスに属さないことが明らかになった。ウラン系強磁性超伝導物質UGe$$_2$$とURhGeでも類似の臨界指数が報告されている。本研究の結果、この新奇な臨界現象は系のキャリア数に依存せず出現することが明らかになった。


Isomer spectroscopy in $$^{133}$$Ba and high-spin structure of $$^{134}$$Ba

Kaya, L.*; Vogt, A.*; Reiter, P.*; Siciliano, M.*; 清水 則孝*; 宇都野 穣; Wang, H.-K.*; Gargano, A.*; Coraggio, L.*; Itaco, N.*; et al.

Physical Review C, 100(2), p.024323_1 - 024323_18, 2019/08



Search of QCD phase transition points in the canonical approach of the NJL model

若山 将征*; 保坂 淳

Physics Letters B, 795, p.548 - 553, 2019/08

We study the Lee-Yang zeros in the canonical approach to search phase transition points at finite temperature and density in the Nambu-Jona-Lasinio (NJL) model as an effective model of QCD. The canonical approach is a promising method to avoid the sign problem in lattice QCD at finite density. We find that a set of Lee-Yang zeros computed with finite degrees of freedom can be extrapolated to those with infinite degrees of freedom, providing the correct phase transition point. We propose the present method as a useful method for actual lattice simulations for QCD.


Vector and Axial-vector form factors in radiative kaon decay and flavor SU(3) symmetry breaking

Shim, S.-I.*; 保坂 淳; Kim, H.-C.*

Physics Letters B, 795, p.438 - 445, 2019/08

We study the vector and axial-vector form factors of radiative kaon decay within the framework of the gauged nonlocal effective chiral action from the instanton vacuum, focusing on the effects of flavor SU(3) symmetry breaking. The general tendency of the results are rather similar to those of radiative pion decays: The nonlocal contributions make the results of the vector form factor increased by about 20%, whereas they reduce those of the axial-vector form factor by almost 50%. Suppressing the prefactors consisting of the kaon mass and the pion decay constant, we scrutinize how the kaon form factors undergo changes as the mass of the strange current quark is varied. Those related to the vector and second axial-vector form factors tend to decrease monotonically as the strange quark mass increases, whereas that for the axial-vector form factor decreases. When $$Kto enugamma$$ decay is considered, both the results of the vector and axial-vector form factors at the zero momentum transfer are in good agreement with the experimental data. The results are also compared with those from chiral perturbation theory to $$p^6$$ order.


Hadronic Paschen-Back effect in charmonium

岩崎 幸生; 岡 眞; 鈴木 渓*; 吉田 哲也*

AIP Conference Proceedings 2130, p.050001_1 - 050001_8, 2019/07



Possibility of a new narrow $$Lambda^*$$ resonance near the $$Lambda eta$$ threshold

谷田 聖

AIP Conference Proceedings 2130, p.040019_1 - 040019_6, 2019/07

Evidence for a narrow $$Lambda^*$$ resonance at a mass of about 1665 MeV (just above the combined mass of the $$Lambda$$ ground state plus the $$eta$$ meson) has been seen in the $$M(pK^-)$$ mass of the Dalitz plot for $$Lambda_c to pK^-pi^+$$ decay at the Belle experiment. Additional evidence for this resonance is found in the partial-wave analysis (PWA) of data on $$K^- p$$ reactions done independently by several groups, driven by angular distributions of the $$K^- p to Lambdaeta$$ reaction by the Crystal Ball collaboration. If a narrow $$Lambda^*$$ resonance exists at this mass, then the conventional quark model cannot explain it, and a possible explanation is that it is a crypto-exotic baryon with a dominant meson-baryon component to its wave function. Therefore we have proposed a definitive experiment for $$K^- p to Lambda eta$$, using the newly built hypTPC detector to establish the existence of the proposed narrow $$Lambda(1665)$$ and determine its spin and parity in just two weeks of beamtime at J-PARC (E72). We will discuss these evidences for the proposed $$Lambda^*$$ resonance and introduce the E72 experiment.


Exotic and conventional quarkonium physics prospects at Belle II

谷田 聖

AIP Conference Proceedings 2130, p.040020_1 - 040020_6, 2019/07

The Belle II experiment, now operating at the KEK laboratory in Japan, is a substantial upgrade of both the Belle detector and the KEKB $$e^+ e^-$$ accelerator. It aims to collect 50 times more data than existing B-Factory samples. Belle II is uniquely capable to study the so-called "XYZ" particles: heavy exotic hadrons consisting of more than three quarks. First discovered by Belle, these now number in the dozens, and represent the emergence of a new category within quantum chromodynamics. This talk will present the capabilities of Belle II to explore both exotic and conventional quarkonium physics.


Current-induced modulation of coercive field in the ferromagnetic oxide SrRuO$$_{3}$$

山ノ内 道彦*; 小山田 達郎*; 佐藤 晃一*; 太田 裕道*; 家田 淳一

IEEE Transactions on Magnetics, 55(7), p.1400604_1 - 1400604_4, 2019/07

We investigated the coercive field $$H_{c}$$ for Domain Wall (DW) motion as a function of the current $$I$$ in the ferromagnetic oxide SrRuO$$_{3}$$, a model system with narrow DWs for fabricating high-density spintronics devices. The DW is moved by $$I$$ in the direction of the current, and $$H_{c}$$ is modulated linearly in $$I$$. This linear relationship is consistent with an effective magnetic field $$H_{eff}$$ driving the DW. The direction of DW motion and the magnitude of $$H_{eff}$$ are well described by a model based on the field-like torque arising from the spin relaxation of conduction electrons in the DW.


Hadronic Paschen-Back effect in P-wave charmonia under strong magnetic fields

岩崎 幸生; 岡 眞; 鈴木 渓*; 吉田 哲也*

International Journal of Modern Physics; Conference Series (Internet), 49, p.1960002_1 - 1960002_6, 2019/07



$$^{125}$$Te-NMR study on a single crystal of heavy fermion superconductor UTe$$_2$$

徳永 陽; 酒井 宏典; 神戸 振作; 服部 泰佑; 比嘉 野乃花; 仲嶺 元輝*; 北川 俊作*; 石田 憲二*; 仲村 愛*; 清水 悠晴*; et al.

Journal of the Physical Society of Japan, 88(7), p.073701_1 - 073701_4, 2019/07

最近新たに発見された重い電子系超伝導体UTe$$_2$$$$^{125}$$Te-NMRによる研究について報告する。単結晶試料を用い$$^{125}$$Te-NMRのKnight shift $$K$$およびスピン-格子緩和率$$1/T_1$$の測定を行なった。その結果、20K以上の常磁性相において静的および動的帯磁率のどちらもが弱いIsing型の異方性を持つことを確認した。一方、20K以下の低温ではa軸方向に磁場をかけた場合にスピン-スピン緩和率$$1/T_2$$の強い発散が見られることがわかった。このことは低温でa軸方向に強い縦型のスピン揺らぎが発達していることを示唆している。


Universal $$frac{1}{3}$$-suppression of magnonic shot noise in diffusive insulating magnets

仲田 光樹; 大沼 悠一*; 松尾 衛*

Physical Review B, 100(1), p.014406_1 - 014406_8, 2019/07


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