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Meer, H.*; Wust, S.*; Schmitt, C.*; Herrgen, P.*; Fuhrmann, F.*; Hirtle, S.*; Bednarz, B.*; Rajan, A.*; Ramos, R.*; Nio, M. A.*; et al.
Advanced Functional Materials, 33(21), p.2213536_1 - 2213536_6, 2023/05
被引用回数:0 パーセンタイル:54.89(Chemistry, Multidisciplinary)The antiferromagnetic order in heterostructures of NiO/Pt thin films can be modified by optical pulses. After the irradiation with laser light, the optically induced creation of antiferromagnetic domains can be observed by imaging the created domain structure utilizing the X-ray magnetic linear dichroism effect. The effect of different laser polarizations on the domain formation can be studied and used to identify a polarization-independent creation of 180 domain walls and domains with 180 different Nel vector orientation. By varying the irradiation parameters, the switching mechanism can be determined to be thermally induced. This study demonstrates experimentally the possibility to optically create antiferromagnetic domains, an important step towards future functionalization of all optical switching mechanisms in antiferromagnets.
Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; Gmez-Ramos, M.*; 緒方 一介*; 吉田 数貴; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.
Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04
被引用回数:5 パーセンタイル:92.42(Physics, Multidisciplinary)大きなフェルミ面非対称性を持つ陽子過剰なO原子核からの100MeV/nucleonでの陽子による陽子・中性子除去反応について報告した。この結果は、quasi-freeノックアウト反応、非弾性散乱、核子移行反応を含む複数の反応機構の定量的寄与を初めて示すものである。このようなエネルギー領域では通常無視される非弾性散乱と核子移行の寄与が、弱束縛陽子と強束縛中性子の除去反応断面積にそれぞれ約50%と30%寄与していることが示された。
Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; Gmez-Ramos, M.*; et al.
Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10
被引用回数:5 パーセンタイル:46.8(Physics, Nuclear)理化学研究所のRIビームファクトリーにて中性子過剰Clの励起状態をArからのノックアウト反応によって生成し、脱励起ガンマ線からそのエネルギー準位を測定した。また、陽子ノックアウトの運動量分布からClの基底状態がであることがわかった。その結果を大規模殻模型計算およびいくつかの第一原理計算と比較した。Cl同位体の基底状態および第一励起状態は、計算で用いた相互作用に敏感であることがわかった。それは、陽子の一粒子エネルギーと四重極集団運動との複雑な結合によるためであると考えられる。
Schmitt, C.*; Lemasson, A.*; Schmidt, K.-H.*; Jhingan, A.*; Biswas, S.*; Kim, Y. H.*; Ramos, D.*; Andreyev, A. N.; Curien, D.*; Ciemala, M.*; et al.
Physical Review Letters, 126(13), p.132502_1 - 132502_6, 2021/04
被引用回数:15 パーセンタイル:84.11(Physics, Multidisciplinary)Isotopic distributions of fragments from fission of the neutron-deficient Hg nuclide are reported. This experimental observable is obtained for the first time in the region around lead using an innovative approach based on inverse kinematics and the coincidence between the large acceptance magnetic spectrometer VAMOS++ and a new detection arm close to the target. The average fragment ratio and prompt neutron multiplicity are derived and compared with current knowledge from actinide fission. A striking consistency emerges, revealing the unexpected dominant role of the proton subsystem with atomic number between the = 28 and 50 magic numbers. The origin of nuclear charge polarization in fission and fragment deformation at scission are discussed.
Prez Snchez, R.*; Jurado, B.*; Mot, V.*; Roig, O.*; Dupuis, M.*; Bouland, O.*; Denis-Petit, D.*; Marini, P.*; Mathieu, L.*; Tsekhanovich, I.*; et al.
Physical Review Letters, 125(12), p.122502_1 - 122502_5, 2020/09
被引用回数:13 パーセンタイル:70.32(Physics, Multidisciplinary)Reliable neutron-induced-reaction cross sections of unstable nuclei are essential for nuclear astrophysics and applications but their direct measurement is often impossible. The surrogate-reaction method is one of the most promising alternatives to access these cross sections. In this work, we successfully applied the surrogate-reaction method to infer for the first time both the neutron-induced fission and radiative capture cross sections of Pu in a consistent manner from a single measurement. This was achieved by combining simultaneously measured fission and -emission probabilities for the Pu(He, He') surrogate reaction with a calculation of the angular-momentum and parity distributions populated in this reaction. While other experiments measure the probabilities for some selected -ray transitions, we measure the -emission probability. This enlarges the applicability of the surrogate-reaction method.
Frotscher, A.*; Gmez-Ramos, M.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; 馬場 秀忠*; Orlandi, R.; 他86名*
Physical Review Letters, 125(1), p.012501_1 - 012501_7, 2020/07
被引用回数:5 パーセンタイル:38.78(Physics, Multidisciplinary)Twenty-one two-proton () knock-out cross sections of neutron-rich radioactive isotopes were measured in inverse kinematics using the MINOS time-projection chamber at RIBF, RIKEN. The proton angular distributions, measured for the first time, reveal that the reaction kinematics of the () reaction is consistent with sequential proton collisions within the projectile nucleus.
Chrysalidis, K.*; Barzakh, A. E.*; Ahmed, R.*; Andreyev, A. N.; Ballof, J.*; Cubiss, J. G.*; Fedorov, D. V.*; Fedosseev, V. N.*; Fraile, L. M.*; Harding, R. D.*; et al.
Nuclear Instruments and Methods in Physics Research B, 463, p.472 - 475, 2020/01
被引用回数:3 パーセンタイル:36.4(Instruments & Instrumentation)放射壊変によって生成された多数のジスプロシウム同位体について、ISOLDEのレーザー共鳴イオン源(RILIS)を用いてイオン源内レーザー分光法によって研究した。Dyに対する相対的な同位体シフトを (gs) 共鳴遷移を用いて測定した。電子的因子Fとマスシフト因子Mを導出し、それらを使ってDyとDyの平均自乗荷電半径の変化を初めて決定した。
関原 隆泰; Oset, E.*; Ramos, A.*
JPS Conference Proceedings (Internet), 26, p.023009_1 - 023009_4, 2019/11
In this contribution we theoretically investigate what is the origin of the peak structure observed in the E15 experiment at J-PARC. Since the peak exists near the threshold, we expect two scenarios to produce the peak. One is that the is generated but it does not correlate with , and the uncorrelated - system subsequently decays into . The other is that the quasi-bound state is indeed generated and decays into . We calculate the invariant mass spectrum of the reaction with these two scenarios and compare it with the experimental one to interpret the experimental peak structure.
Ramos, R.*; 日置 友智*; 橋本 佑介*; 吉川 貴史*; Frey, P.*; Kreil, A. J. E.*; Vasyuchka, V. I.*; Serga, A. A.*; Hillebrands, B.*; 齊藤 英治
Nature Communications (Internet), 10, p.5162_1 - 5162_8, 2019/11
被引用回数:23 パーセンタイル:76.88(Multidisciplinary Sciences)Resonant enhancement of spin Seebeck effect (SSE) due to phonons was recently discovered in YFeO (YIG). This effect is explained by hybridization between the magnon and phonon dispersions. However, this effect was observed at low temperatures and high magnetic fields, limiting the scope for applications. Here we report observation of phonon-resonant enhancement of SSE at room temperature and low magnetic field. We observe in LuBiFeGaO an enhancement 700% greater than that in a YIG film and at very low magnetic fields around 10 T, almost one order of magnitude lower than that of YIG. The result can be explained by the change in the magnon dispersion induced by magnetic compensation due to the presence of non-magnetic ion substitutions. Our study provides a way to tune the magnon response in a crystal by chemical doping, with potential applications for spintronic devices.
吉川 貴史*; 鈴木 基寛*; Ramos, R.*; Aguirre, M. H.*; 岡林 潤*; 内田 健一*; Lucas, I.*; Anadn, A.*; 菊池 大介*; Algarabel, P. A.*; et al.
Journal of Applied Physics, 126(14), p.143903_1 - 143903_11, 2019/10
被引用回数:10 パーセンタイル:49.82(Physics, Applied)Induced Pt ferromagnetism in FeO/Pt/FeO epitaxial trilayer films has been investigated by means of X-ray magnetic circular dichroism (XMCD) at the Pt -edges at various temperatures from 300 K to 12 K, including the metal-insulator transition temperature of FeO ( K). At all the temperatures, we observed clear XMCD signals due to Pt ferromagnetism, the amplitude of which was determined to be 0.39 at 300K and 0.52 at 12 K for the sample with the Pt thickness of nm. Interestingly, these values are comparable to or even greater than those in Pt/3-ferromagnetic-metal (Fe, Ni, Co, and NiFe) junction systems. The results can be interpreted in terms of a possible Fe interdiffusion into the Pt layer and also possible Fe-Pt alloying due to its high-temperature deposition.
Baldrati, L.*; Gomonay, O.*; Ross, A.*; Filianina, M.*; Lebrun, R.*; Ramos, R.*; Leveille, C.*; Fuhrmann, F.*; Forrest, T. R.*; Maccherozzi, F.*; et al.
Physical Review Letters, 123(17), p.177201_1 - 177201_6, 2019/10
被引用回数:118 パーセンタイル:98.44(Physics, Multidisciplinary)We probe the current-induced magnetic switching of insulating antiferromagnet-heavy-metal systems, by electrical spin Hall magnetoresistance measurements and direct imaging, identifying a reversal occurring by domain wall (DW) motion. We observe switching of more than one-third of the antiferromagnetic domains by the application of current pulses. Our data reveal two different magnetic switching mechanisms leading together to an efficient switching, namely, the spin-current induced effective magnetic anisotropy variation and the action of the spin torque on the DWs.
Wrzosek-Lipska, K.*; Rezynkina, K.*; Bree, N.*; Zieliska, M.*; Gaffney, L. P.*; Petts, A.*; Andreyev, A. N.; Bastin, B.*; Bender, M.*; Blazhev, A.*; et al.
European Physical Journal A, 55(8), p.130_1 - 130_23, 2019/08
被引用回数:11 パーセンタイル:74.44(Physics, Nuclear)The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0, 2, and 4 states was observed in all nuclei under study. Reduced matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.
Dong, B.-W.*; Baldrati, L.*; Schneider, C.*; 新関 友彦*; Ramos, R.*; Ross, A.*; Cramer, J.*; 齊藤 英治; Klui, M.*
Applied Physics Letters, 114(10), p.102405_1 - 102405_5, 2019/03
被引用回数:11 パーセンタイル:49.82(Physics, Applied)We study the spin Hall magnetoresistance (SMR) in epitaxial -FeO/NiO(001)/Pt stacks, as a function of temperature and thickness of the antiferromagnetic insulating NiO layer. Upon increasing the thickness of NiO from 0 nm to 10 nm, we detect a sign change of the SMR in the temperature range between 10 K and 280 K. This temperature dependence of the SMR in our stacks is different compared to that of previously studied yttrium iron garnet/NiO/Pt, as we do not find any peak or sign change as a function of temperature. We explain our data by a combination of spin current reflection from both the NiO/Pt and -FeO/NiO interfaces and the thickness-dependent exchange coupling mode between the NiO and -FeO layers, comprising parallel alignment for thin NiO and perpendicular alignment for thick NiO.
関原 隆泰; Oset, E.*; Ramos, A.*
Proceedings of Science (Internet), 310, p.199_1 - 199_5, 2018/03
In this contribution we theoretically investigate what is the origin of the peak structure observed in the E15 experiment at J-PARC. Since the peak exists near the threshold, we expect two scenarios to produce the peak. One is that the is generated but it does not correlate with , and the uncorrelated - system subsequently decays into . The other is that the quasi-bound state is indeed generated and decays into . We calculate the invariant mass spectrum of the reaction with these two scenarios and compare it with the experimental one to interpret the experimental peak structure.
関原 隆泰; Oset, E.*; Ramos, A.*
Acta Physica Polonica B, 48(10), p.1869 - 1874, 2017/10
被引用回数:1 パーセンタイル:12.03(Physics, Multidisciplinary)In this contribution we theoretically investigate what is the origin of the peak structure observed in the E15 experiment at J-PARC. Since the peak exists near the threshold, we expect two scenarios to produce the peak. One is that the is generated but it does not correlate with , and the uncorrelated - system subsequently decays into . The other is that the quasi-bound state is indeed generated and decays into . We calculate the invariant mass spectrum of the reaction with these two scenarios and compare it with the experimental one to interpret the experimental peak structure.
Ramos, R.*; 吉川 貴史*; Anadn, A.*; Lucas, I.*; 内田 健一*; Algarabel, P. A.*; Morelln, L.*; Aguirre, M. H.*; 齊藤 英治; Ibarra, M. R.*
AIP Advances (Internet), 7(5), p.055915_1 - 055915_7, 2017/05
被引用回数:19 パーセンタイル:65.79(Nanoscience & Nanotechnology)We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers formed by repeated growth of a FeO/Pt bilayer junction. The magnitude of the observed enhancement of the SSE, relative to the SSE in the single bilayer, shows a monotonic increase with decreasing the temperature. This result can be understood by an increase of the characteristic length for spin current transport in the system, in qualitative agreement with the recently observed increase in the magnon diffusion length in FeO at lower temperatures. Our result suggests that the thermoelectric performance of the SSE in multilayer structures can be further improved by careful choice of materials with suitable spin transport properties.
関原 隆泰; Oset, E.*; Ramos, A.*
JPS Conference Proceedings (Internet), 13, p.020002_1 - 020002_5, 2017/02
In this contribution we theoretically investigate what is the origin of the peak structure observed in the E15 experiment at J-PARC. Since the peak exists near the threshold, we expect two scenarios to produce the peak. One is that the is generated but it does not correlate with , and the uncorrelated - system subsequently decays into . The other is that the quasi-bound state is indeed generated and decays into . We calculate the invariant mass spectrum of the reaction with these two scenarios and compare it with the experimental one to interpret the experimental peak structure.
関原 隆泰; Oset, E.*; Ramos, A.*
Progress of Theoretical and Experimental Physics (Internet), 2016(12), p.123D03_1 - 123D03_27, 2016/12
被引用回数:37 パーセンタイル:85.97(Physics, Multidisciplinary)In this contribution we theoretically investigate what is the origin of the peak structure observed in the E15 experiment of the in-flight He( reaction at J-PARC, which could be a signal of the lightest kaonic nuclei, that is, the state. For the investigation, we evaluate the invariant mass spectrum assuming two possible scenarios to interpret the experimental peak. One assumes that the resonance is generated after the emission of an energetic neutron from the absorption of the initial , not forming a bound state with the remaining proton. The other scenario implies that, after the emission of the energetic neutron, a bound state is formed. Our results show that the experimental signal observed in the in-flight He( reaction at J-PARC is qualitatively well reproduced by the assumption that a bound state is generated in the reaction, definitely discarding the interpretation in terms of an uncorrelated state.
Ramos, R.*; 吉川 貴史*; Aguirre, M.*; Lucas, I.*; Anadn, A.*; 小宅 教文*; 内田 健一*; 安立 裕人; 塩見 淳一郎*; Algarabel, P. A.*; et al.
Physical Review B, 92(22), p.220407_1 - 220407_5, 2015/12
被引用回数:69 パーセンタイル:90.84(Materials Science, Multidisciplinary)Spin Seebeck effects have been investigated in highly crystalline magnetic multilayer films. Voltage as well as power generated by the spin Seebeck effect were found to be significantly enhanced with increasing the number of layers, . This voltage enhancement defies the simple understanding of the spin Seebeck effect and suggests that spin current flowing between the magnetic layers in the thickness direction plays an important role in the multilayer SSE systems and the observed voltage enhancement.
Ramos, R.*; Aguirre, M. H.*; Anadn, A.*; Blasco, J.*; Lucas, I.*; 内田 健一*; Algarabel, P. A.*; Morelln, L.*; 齊藤 英治; Ibarra, M. R.*
Physical Review B, 90(5), p.054422_1 - 054422_6, 2014/08
被引用回数:90 パーセンタイル:93.85(Materials Science, Multidisciplinary)We report a complete characterization of the anomalous Nernst effect (ANE) and its relationship with the anomalous Hall effect (AHE) in FeO. By combining full thermoelectric and electric transport measurements as a function of temperature, we have verified that the universal scaling relation between the anomalous Hall and diagonal conductivities, observed in materials with bad-metal-hopping type of conduction, is also applicable to the thermoelectric transport. We further show that the ANE and AHE are commonly related through the Mott relation, therefore demonstrating its validity for anomalous transport phenomena in materials with conduction in the dirty regime.