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論文

Physical properties of intergrowth compound Eu $_{2}$ CuZn $_{2}$ P $_{3}$

May, A. F.*; 田端千紘; Okamoto, Satoshi*; Ortiz, B. R.*; Christianson, A. D.*; Yan, J.*; 金子耕士; McGuire, M. A.*

Physical Review Materials (Internet), 9(2), p.024406_1 - 024406_13, 2025/02

https://doi.org/10.1103/PhysRevMaterials.9.024406

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

The physical properties of single crystalline Eu $_{2}$ CuZn $_{2}$ P $_{3}$ were inspected via thermodynamic, transport, and neutron diffraction measurements. Eu $_{2}$ CuZn $_{2}$ P $_{3}$ is composed of EuCuP and EuZn $_{2}$ P $_{2}$ motifs stacked in a one-to-one ratio. The magnetic response of Eu $_{2}$ CuZn $_{2}$ P $_{3}$ is similar to that of EuZn $_{2}$ P $_{2}$ in its A-type antiferromagnetic (semiconducting) form.

論文

Magnetic excitations in the noncentrosymmetric magnet Sr $_{2}$ MnSi $_{2}$ O $_{7}$

川又雅広*; Pang, X.*; 村川寛*; 河村聖子; 中島健次; 増田英敏*; 藤田全基*; 花咲徳亮*; 小野瀬佳文*; 南部雄亮*

Physical Review Materials (Internet), 9(1), p.014407_1 - 014407_6, 2025/01

https://doi.org/10.1103/PhysRevMaterials.9.014407

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

Magnetic excitations in the noncentrosymmetric magnet Sr $_{2}$ MnSi $_{2}$ O $_{7}$ were investigated through inelastic neutron scattering measurements. Major magnetic excitations are limited up to the energy transfer of 0.5 meV, and two magnon branches under zero magnetic field were well explained in the framework of linear spinwave theory. The magnitudes of the square-lattice in-plane and interplane nearest-neighbor interactions, spin anisotropy term, and the Dzyaloshinskii-Moriya interaction are, respectively, estimated to be J $_{1}$ = 45.54(5) eV, J $_{2}$ = 0.52(1) eV, = 4.98(11) eV, D $_{xy}$ = 0.02(9) eV, and D $_{z}$ = 4.10(1) eV, and calculations using these parameters reproduce experimental data quite well. Sr $_{2}$ MnSi $_{2}$ O $_{7}$ appears to have the smallest energy scale among the melilite-type compounds, and the small J $_{2}$ /J $_{1}$ = 0.0114(2) indicates the strong two dimensionality.

論文

Possible field-induced quantum state in a rhombic lattice antiferromagnet KCoPO $_{4}$ H $_{2}$ O

藤原理賀; 萩原雅人; 幸田章宏*; 中村惇平*; 松尾晶*; 金道浩一*; 石角元志*

Physical Review Materials (Internet), 9(1), p.014406_1 - 014406_9, 2025/01

https://doi.org/10.1103/PhysRevMaterials.9.014406

被引用回数：1 パーセンタイル：0.00(Materials Science, Multidisciplinary)

We reported the magnetic behavior of a rhombic lattice quantum antiferromagnet KCoPO $_{4}$ H $_{2}$ O. The rhombic lattice model is equivalent to a model of a square lattice with two different diagonal components, and competing exchange interactions potentially produce exotic quantum states. This compound is well characterized by the $_{rm{eff}}$ = 1/2 state. The magnetic structure of KCoPO $_{4}$ H $_{2}$ O is identified as an incommensurate helical structure, characterized by a magnetic modulation propagation vector = (0.1747(1) 0 0) with an in-plane moment rotating along the axis. Moreover, a magnetic field-induced phase transition is observed at approximately 1 T. The application of a magnetic field suppresses spin ordering and enhance spin fluctuations. Our experimental results suggest the presence of a quantum phase in the magnetic phase diagram of the spin-1/2 Heisenberg rhombic lattice antiferromagnet with easy-plane anisotropy.

論文

Surface structure of the 33-Si phase on Al(111), studied by the multiple usages of positron diffraction and core-level photoemission spectroscopy

佐藤祐輔*; 深谷有喜; 他14名*

Physical Review Materials (Internet), 9(1), p.014002_1 - 014002_11, 2025/01

https://doi.org/10.1103/PhysRevMaterials.9.014002

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

本研究では、陽電子回折と内殻光電子分光の複合利用により、Al(111)33-Si表面の構造を明らかにした。ロッキング曲線の解析では、33-Si相が平坦なハニカム構造から構成されること、また、第一原理計算に基づくSi内殻スペクトルの解析では、単位胞内のSi原子の一つがAl原子と置換されていることがわかった。すなわち、33-Si相の表面超構造はAl原子を内包したSi二次元層である。

論文

Continuous structural phase transition and antiferromagnetic order in ilmenite-type NiVO $_{3}$

山本孟*; 池田理*; 本田孝志*; 木村健太*; 青山拓也*; 大串研也*; 鈴木昭夫*; 石井賢司*; 松村大樹; 辻卓也; et al.

Physical Review Materials (Internet), 8(9), p.094402_1 - 094402_6, 2024/09

https://doi.org/10.1103/PhysRevMaterials.8.094402

被引用回数：2 パーセンタイル：56.91(Materials Science, Multidisciplinary)

We investigate the crystal and electronic structures as well as magnetic properties of ilmenite-type NiVO $_{3}$ , which has attracted research interest as an = 1 honeycomb lattice magnet. Ilmenite-type NiVO $_{3}$ samples were synthesized under high-pressure and high-temperature conditions. Synchrotron X-ray diffraction and Rietveld refinement results demonstrated that NiVO $_{3}$ underwent a continuous structural phase transition from the triclinic () phase to the rhombohedral () phase at 450 K. This transition is concomitant with the decomposition of the V-V dimers formed by the tetravalent V ions. X-ray absorption spectroscopy measurements confirmed that the Ni and V ions were divalent and tetravalent, respectively. Magnetic and specific heat measurements revealed that NiVO $_{3}$ underwent an antiferromagnetic transition at 140 K, and a zigzag-type magnetic order with magnetic propagation vector =(0,1/2,0) was observed by neutron diffraction measurements.

論文

Dramatic elastic response at the critical end point in UTe

Valika, M.*; Haidamak, T.*; Cabala, A.*; Pospil, J.*; Bastien, G.*; Sechovsk, V.*; Prokleka, J.*; 柳澤達也*; Opletal, P.; 酒井宏典; et al.

Physical Review Materials (Internet), 8(9), p.094415_1 - 094415_9, 2024/09

https://doi.org/10.1103/PhysRevMaterials.8.094415

被引用回数：2 パーセンタイル：0.00(Materials Science, Multidisciplinary)

Elastic responses at the metamagnetic transition in UTe are studied at high field. The elastic anomaly becomes the strongest at the critical-end-point. Similar behavior was also observed in another metamagnet UCoAl, suggesting a universal elastic response triggered by critical magnetic fluctuations.

論文

Tuning of spin-orbit coupling in chiral molecule-incorporated two-dimensional organic-inorganic hybrid perovskite copper halides with ferromagnetic exchange interactions

谷口耕治*; Huang, P.-J.*; 佐賀山基*; 鬼柳亮嗣; 大石一城*; 鬼頭俊介*; 中村唯我*; 宮坂等*

Physical Review Materials (Internet), 8(2), p.024409_1 - 024409_10, 2024/02

https://doi.org/10.1103/PhysRevMaterials.8.024409

被引用回数：2 パーセンタイル：56.91(Materials Science, Multidisciplinary)

Leveraging the flexible material designability of organic-inorganic hybrid systems, spatial inversion symmetry breaking and spin-orbit coupling (SOC) were simultaneously controlled in a series of two-dimensional organic-inorganic hybrid perovskite (2D-OIHP) copper halides with ferromagnetic exchange interaction (FMI). In chiral molecule-incorporated 2D-OIHP copper halides, an increase in Br component over Cl component at halogen sites leads to systematic variations in magnetic phase diagrams owing to the competition between the FMI and Dzyaloshinskii-Moriya interaction induced by the SOC. The crucial role of noncentrosymmetry in the competition for the magnetic interactions was confirmed by comparing the magnetic phase diagrams of chiral and achiral 2D-OIHP copper bromides.

論文

Effect of Mn substitution on the electronic structure for Mn-doped indium-tin oxide films studied by soft and hard X-ray photoemission spectroscopy

大槻太毅*; Ishida, Tatsuhiro*; Tsutsumi, Naoya*; 小林正起*; Inagaki, Kodai*; 吉田鉄平*; 竹田幸治; 藤森伸一; 保井晃*; 北川彩貴*; et al.

Physical Review Materials (Internet), 7(12), p.124601_1 - 124601_6, 2023/12

https://doi.org/10.1103/PhysRevMaterials.7.124601

被引用回数：2 パーセンタイル：21.90(Materials Science, Multidisciplinary)

In $_{1.8-x}$ MnSn $_{0.2}$ O is a diluted magnetic semiconductor combining transparent, ferromagnetism, and semiconducting properties. We report the electronic structure of In $_{1.8-x}$ MnSn $_{0.2}$ O (x = 0.0, 0.2, and 0.3) by means of hard X-ray photoemission spectroscopy (HAXPES), soft X-ray resonant photoemission spectroscopy (RPES), and X-ray absorption spectroscopy (XAS). The spectral shape of the Mn - XAS spectra indicates that the valence of the substitutional Mn ions is divalent. The In 3 and O core-level shifts with Mn substitution suggest the hole doping due to the Mn $^{2+}$ ions. The valence-band spectra exhibit the well-defined features associated with the donor states across the Fermi level (EF) and the valence-band edge. The valence-band maximum (VBM) shifts to higher binding energy and the spectral weight near EF decreases with increasing Mn concentration, which is consistent with the hole doping nature observed in the core-level shift. The Mn -3 RPES reveals that the hump structure around 1.9 eV above the VBM is originating from the Mn 3 impurity band and the valence-band state consists of the O 2 band strongly hybridized with the Mn 3 orbital. Furthermore, there is no contribution of the Mn 3 orbital to the spectral weight close to $E_{rm F}$ . Based on our results, we argue the possible mechanism of the ferromagnetism for In $_{1.8-x}$ MnSn $_{0.2}$ O.

論文

Local atomic structures and lattice dynamics of inverse colossal barocaloric ammonium thiocyanate

Zhang, Z.*; Gong, W.; 川北至信; 他9名*

Physical Review Materials (Internet), 7(12), p.125402_1 - 125402_9, 2023/12

https://doi.org/10.1103/PhysRevMaterials.7.125402

被引用回数：2 パーセンタイル：21.90(Materials Science, Multidisciplinary)

NH $_{4}$ SCN exhibits successive phase transitions from monoclinic to orthorhombic, and then to tetragonal. The former phase transition is accompanied by an inverse colossal barocaloric effect and a huge negative thermal expansion. This transition is complicated by the possibly coexisting orientational disorder of NH $_{4}$ $^{+}$ and SCN $^{-}$ , and the mechanism is still unclear. Here, NH $_{4}$ SCN is investigated using high-resolution neutron powder diffraction, pair distribution function analysis, and Raman scattering. Both the average and local structural analysis indicate that only NH $_{4}$ $^{+}$ is orientationally disordered in the orthorhombic phase and SCN $^{-}$ becomes subsequently disordered in the tetragonal phase. Both temperature-induced and pressure-induced hardening behaviors of SCN $^{-}$ related vibrations are observed, which leads to the breakage of hydrogen bonds-linked NH $_{4}$ $^{+}$ with SCN $^{-}$ and further facilitates phase transition. Our findings provide a solid standing point of atomic structures and dynamics, on which the scenario of the phase transition and the associated physical properties is established.

論文

Controlling dual Mott states by hydrogen doping to perovskite rare-earth nickelates

松澤郁也*; 福谷克之; 他5名*

Physical Review Materials (Internet), 7(8), p.085003_1 - 085003_6, 2023/08

https://doi.org/10.1103/PhysRevMaterials.7.085003

被引用回数：9 パーセンタイル：67.40(Materials Science, Multidisciplinary)

Doping hydrogen in correlated oxides is a promising way to control the materials functionalities. With in situ measurements of the resistance and hydrogen concentration by a nuclear reaction analysis, we have derived the detailed relation between the resistance and hydrogen concentration () for NiO $_{3}$ H $_{x}$ ( = Sm, Nd, and La), which reveal a clear resistance jump at a certain concentration. Taking account of the spatial distribution of hydrogen in both in-plane and depth directions, we have clarified that an insulating state is realized at and another insulating state is formed at . The electronic mechanisms for the two states are proposed in terms of Mott phases.

論文

Dynamic interaction between dislocations and obstacles in BCC iron based on atomic potentials derived using neural networks

森英喜*; 都留智仁; 奥村雅彦; 松中大介*; 椎原良典*; 板倉充洋

Physical Review Materials (Internet), 7(6), p.063605_1 - 063605_8, 2023/06

https://doi.org/10.1103/PhysRevMaterials.7.063605

被引用回数：3 パーセンタイル：32.83(Materials Science, Multidisciplinary)

析出物などの障害物を導入して転位の動きを制御することは、金属の機械的強度を設計するための有力な方法である。転位コアのサイズは1nm以下とナノスケールであるため、転位と障害物の相互作用を調べるには、原子レベルのモデリングが必要である。しかし、従来の経験的ポテンシャルでは十分な精度が得られなかったため、転位と障害物の相互作用の原子レベルでの詳細が解明されていない。そこで、本研究では、人工ニューラルネットワーク(ANN)の枠組みを用い、第一原理計算の高精度を生かした原子ポテンシャルを構築した。構築したANNポテンシャルを用いて、BCC鉄における $(a_0/2){110}$ 刃状転位と障害物の動的相互作用を調査した。転位が空隙を横切ると、Bow-out転位では超平滑で対称的な半ループが観察された。らせん転位を除き、ANNを用いて予測されたすべての転位のパイエルス応力は100MPa以下であった。さらに重要なことは、剛体球と転位の相互作用において、オロワンループが形成されることを確認したことである。さらに、オロワンループが剛体球と転位の相互作用の中で、2つの小さなループに分解する現象を発見した。

論文

Origin of magnetically dead layers in spinel ferrites FeO grown on AlO; Effects of postdeposition annealing studied by XMCD

野中洋亮*; 若林勇希*; 芝田悟朗; 坂本祥哉*; 池田啓祐*; Chi, Z.*; Wan, Y.*; 鈴木雅弘*; 田中新*; 田中雅明*; et al.

Physical Review Materials (Internet), 7(4), p.044413_1 - 044413_10, 2023/04

https://doi.org/10.1103/PhysRevMaterials.7.044413

被引用回数：5 パーセンタイル：50.30(Materials Science, Multidisciplinary)

We study the electronic and magnetic states of as-grown and annealed FeO(111)/AlO3(111) (Co, Ni) thin films with various thicknesses grown on Si(111) substrates with the -AlO(111)buffer layers by using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD), to investigate magnetically dead layers in these films. Although the magnetically dead layers in the as-grown samples are formed near the interface with the AlO buffer layer, we reveal that ferrimagnetic order is partially recovered by postdeposition annealing at 973 K for 48 hours in air. By analyzing the line shapes of the XAS and XMCD spectra, we conclude that, in the dead layers, there are a significant number of vacancies at the sites of the spinel structure, which may be the microscopic origin of the degraded ferrimagnetic order in the FeO thin films.

論文

Weyl-Kondo semimetal behavior in the chiral structure phase of Ce $_{3}$ Rh $_{4}$ Sn $_{13}$

岩佐和晃*; Suyama, Kazuya*; 河村聖子; 中島健次; Raymond, S.*; Steffens, P.*; Yamada, Akira*; 松田達磨*; 青木勇二*; 川崎郁斗; et al.

Physical Review Materials (Internet), 7(1), p.014201_1 - 014201_11, 2023/01

https://doi.org/10.1103/PhysRevMaterials.7.014201

被引用回数：4 パーセンタイル：42.21(Materials Science, Multidisciplinary)

The spin dynamics, crystalline-electric-field (CEF) level scheme, specific heat, and X-ray photoemission spectra (XPS) of Ce $_{3}$ Rh $_{4}$ Sn $_{13}$ were investigated, which exhibits anomalous semimetal transport in the chiral crystallographic phase. CEF excitations observed at approximately 7 and 39 meV are consistent with the two inequivalent Ce-ion cites in the chiral structure. Because of broader CEF excitations and a strong 4 $f^{1}$ peak at the Fermi level in the Ce 4 on-resonance spectrum, the hybridized Ce 4 electrons contribute to the semimetal carriers. In addition, the spin fluctuation associated with the Kramers doublet ground state is characterized by the peak located at 0.15 meV. The electronic state involving the spin fluctuation causes the $T^{3}$ behavior of specific heat below 0.6 K, which is attributed to linear dispersion relations of electrons of the Weyl Kondo semimetal in the chiral-lattice symmetry.

論文

Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

寺澤知潮; 松永和也*; 林直輝*; 伊藤孝寛*; 田中慎一郎*; 保田諭; 朝岡秀人

Physical Review Materials (Internet), 7(1), p.014002_1 - 014002_10, 2023/01

https://doi.org/10.1103/PhysRevMaterials.7.014002

被引用回数：7 パーセンタイル：62.75(Materials Science, Multidisciplinary)

金(001)表面は、六角形の表面と正方形のバルク格子からなる複雑な再構成構造[Hex-Au(001)]を示し、擬一次元的な波状表面を形成している。この表面上にグラフェンを成長させると、波状表面の周期性がグラフェンの電子構造を変化させ、バンドギャップや新しいディラックポイントを形成することが予測された。さらに、グラフェン-金界面はバンド混成によるバンドギャップ生成やスピン注入の可能性が期待される。ここでは、Hex-Au(001)表面上のグラフェンについて、角度分解光電子分光と密度汎関数計算を行った結果を報告する。元のグラフェンとレプリカのグラフェンのバンドの交点はバンドギャップを示さず、一次元ポテンシャルが小さすぎて電子構造を変更できないことが示唆された。グラフェンバンドとAu バンドの交点では0.2eVのバンドギャップが観測され、グラフェンバンドとAu バンドの混成を利用してバンドギャップが生成していることが示された。また、グラフェンとAu の混成により、グラフェンへのスピン注入が起こることが予想される。

論文

Incommensurate helimagnetic structure of Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ determined by single-crystal neutron diffraction

田中誠也*; 鬼柳亮嗣; 石川喜久*; 天児寧*; 飯山拓*; 二村竜祐*; 丸山建一*; 内海重宣*

Physical Review Materials (Internet), 7(1), p.014403_1 - 014403_11, 2023/01

https://doi.org/10.1103/PhysRevMaterials.7.014403

被引用回数：1 パーセンタイル：10.57(Materials Science, Multidisciplinary)

Sc-substituted hexagonal ferrite Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ has an incommensurate helimagnetic structure. However, the incommensurate helimagnetic structure has not been sufficiently determined, and the mechanism via which the helimagnetism develops has not been studied. Time-of-flight single-crystal neutron diffraction measurements were performed on single-crystal samples of Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ with Sc concentrations of x = 0, 0.128, 0.153, and 0.193. The magnetic structure analyses revealed that the helimagnetic structure of Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ is a cone type whose base is in the ab plane and height is in the c-axis direction. The magnetic moments of Fe2(4), Fe4(4 $f_{2}$ ), and Fe5(12) are aligned with distinct angles, leading to the helimagnetic structure of Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ , and can be explained by assuming that there is an antiferromagnetic superexchange interaction $J_{5}$ between Fe2(4) and Fe5(12) that is negligible in the x = 0 crystal. The shorter bond distance of Fe2-O1 in Sc-rich crystals revealed by the crystal structure analyses enhances the superexchange interaction $J_{5}$ . The relatively strong $J_{5}$ leads to competition among the three superexchange interactions, $J_{3}$ , $J_{4}$ , and $J_{5}$ , resulting in the development of the helimagnetic structure. These findings facilitate the understanding of the essentials of the basic magnetic material BaFe $_{12}$ O $_{19}$ .

論文

Electrical detection of domain evolution in magnetic Weyl semimetal Co $_{3}$ Sn $_{2}$ S $_{2}$ submicrometer-wide wire devices

塩貝淳一*; 池田絢哉*; 藤原宏平*; 関剛斎*; 高梨弘毅; 塚崎敦*

Physical Review Materials (Internet), 6(11), p.114203_1 - 114203_9, 2022/11

https://doi.org/10.1103/PhysRevMaterials.6.114203

被引用回数：5 パーセンタイル：34.44(Materials Science, Multidisciplinary)

Microscopic understanding of magnetization switching via domain nucleation and/or domain-wall propagation is fundamental knowledge for developing magnetic and spintronic devices. Here, we explore the underlying mechanism of the large coercivity of the magnetic Weyl semimetal Co $_{3}$ Sn $_{2}$ S $_{2}$ thin films, which is roughly ten times larger than that of Co $_{3}$ Sn $_{2}$ S $_{2}$ bulk single crystal, by measuring Hall resistance in constricted wire devices. The discretized steplike variations appear in the hysteresis loops of the Hall resistance in 0.6 micrometers wide and narrower devices, indicating that the size of the reversed magnetic domain is comparable to the active area of the Hall devices. By counting the number of discrete features, the average diameter of the reversed magnetic domain is estimated to be 80 nm. Individually, the diameter of the reversed domain nucleus is evaluated to be roughly 2 nm. Considering the difference in the diameters of the reversed magnetic domain and the reversed domain nucleus, we ascribed the large coercivity of the Co $_{3}$ Sn $_{2}$ S $_{2}$ thin films to a large nucleation field owing to the uniform crystallinity within grains and strong domain-wall pinning at grain boundaries specific to the thin films. With the large nucleation field in the films, an engineering of the domain-wall pinning sites is a promising approach to control the nucleation, manipulation, and detection of the single domain wall in Co $_{3}$ Sn $_{2}$ S $_{2}$ thin-film devices.

論文

Birchite Cd $_{2}$ Cu $_{2}$ (PO $_{4}$ ) $_{2}$ SO $_{4}$ 5H $_{2}$ O as a model antiferromagnetic spin-1/2 Heisenberg $_{1}$ - $_{2}$ chain

藤原理賀; Jeschke, H. O.*; 森田克洋*; 桑井智彦*; 幸田章宏*; 岡部博孝*; 松尾晶*; 金道浩一*; 満田節生*

Physical Review Materials (Internet), 6(11), p.114408_1 - 114408_8, 2022/11

https://doi.org/10.1103/PhysRevMaterials.6.114408

被引用回数：2 パーセンタイル：12.90(Materials Science, Multidisciplinary)

= 1/2ハイゼンベルグ $_{1}$ - $_{2}$ 反強磁性鎖は、エキゾチックなスピン状態の発現が予想されており、広く研究されている。この論文では、birchiteと呼ばれる銅鉱物、化学式Cd $_{2}$ Cu $_{2}$ (PO $_{4}$ ) $_{2}$ SO $_{4}$ 5H $_{2}$ Oの磁気挙動とその有効スピンモデルについて報告する。帯磁率,磁化,比熱,SR測定による実験的研究から、0.4Kまで長距離秩序を示さないことがわかった。理論研究から、birchiteは $_{1}$ - $_{2}$ 反強磁性鎖のモデル化合物であり、鎖内相互作用 $_{1}$ 、 $_{2}$ は反強磁性的で、その大きさは鎖間相互作用の約100倍であることがわかった。 $_{2}$ の大きさは $_{1}$ の大きさの23倍であるため、スピンギャップは $_{1}$ の数%に過ぎないと予想される。比熱の温度依存性は約1Kでブロードなピーク( 0.036 $_{1}$ )を示し、スピンギャップの存在が示唆された。

論文

Composition-tunable magnon-polaron anomalies in spin Seebeck effects in epitaxial BiY $_{3-x}$ FeO $_{12}$ films

吉川貴史*; 齊藤英治; 他6名*

Physical Review Materials (Internet), 6(10), p.104402_1 - 104402_13, 2022/10

https://doi.org/10.1103/PhysRevMaterials.6.104402

被引用回数：7 パーセンタイル：46.06(Materials Science, Multidisciplinary)

We have investigated hybridized magnon-phonon excitation (magnon polarons) in spin Seebeck effects (SSEs) in BiY $_{3-x}$ FeO $_{12}$ (BixY $_{3-x}$ xIG; x=0, 0.5, and 0.9) films with Pt contact. We observed sharp peak structures in the magnetic field H; dependence of the longitudinal SSE (LSSE) voltages, which appear when the phonon dispersions are tangential to the magnon dispersion curve in BixY $_{3-x}$ IG. By increasing the Bi amount x, the peak fields in the LSSE shift toward lower H values due to the reduction of the sound velocities in BixY $_{3-x}$ IG. We also measured the SSE in a nonlocal configuration and found that magnon-polaron anomalies appear with different signs and intensities. Our result shows composition-tunability of magnon-polaron anomalies and provides a clue to further unravel the physics of magnon-polaron SSEs.

論文

Single crystal growth of superconducting UTe by molten salt flux method

酒井宏典; Opletal, P.; 常盤欣文; 山本悦嗣; 徳永陽; 神戸振作; 芳賀芳範

Physical Review Materials (Internet), 6(7), p.073401_1 - 073401_10, 2022/07

https://doi.org/10.1103/PhysRevMaterials.6.073401

被引用回数：50 パーセンタイル：95.07(Materials Science, Multidisciplinary)

スピン三重項超伝導体UTeの新規合成ルートとして溶融塩フラックス法を適用した。合成条件を最適化した結果、今までで最高の超伝導転移温度 $T_{rm c}=2.1$ Kを記録した。これらの単結晶は、著しく大きな残留抵抗率比を示し、 $T_{rm c}$ 以下における残留比熱も小さくなった。これらはウラン空孔による結晶欠陥が減少したことを示しており、溶融塩フラックス中の余剰金属ウランが、還元雰囲気を作り、四価ウランが五価となるのを防ぎウラン空孔生成を抑制しているようだ。また、低融点フラックスがテルルの蒸発を防ぐ効果も期待できる。

論文

Bragg edge tomography characterization of additively manufactured 316L steel

Busi, M.*; Polatidis, E.*; Malamud, F.*; Kockelmann, W.*; Morgano, M.*; Kaestner, A.*; Tremsin, A.*; Kalentics, N.*; Log, R.*; Leinenbach, C.*; et al.

Physical Review Materials (Internet), 6(5), p.053602_1 - 053602_8, 2022/05

https://doi.org/10.1103/PhysRevMaterials.6.053602

被引用回数：12 パーセンタイル：65.51(Materials Science, Multidisciplinary)

In this work we perform a neutron Bragg edge tomography of stainless steel 316L additive manufacturing samples, one as built via standard laser powder bed fusion, and one using the novel three-dimensional (3D) laser shock peening technique. First, we consider conventional attenuation tomography of the two samples by integrating the signal for neutron wavelengths beyond the last Bragg edge, to analyze the bulk density properties of the material. Second, we obtain strain maps for each of the tomography projections by tracking the wavelength of the strongest Bragg edge corresponding to the {111} lattice plane family. It is found that not only the volume of the sample where the shock peening treatment was carried out yields a higher bulk density, but also a deep and remarkable compressive strain region.