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論文

放射性セシウム捕捉ポテンシャルから推定される$$K$$$$_{rm d}$$値と実測$$K$$$$_{rm d}$$値との誤差要因の解明

宇野 功一郎*; 中尾 淳*; 奥村 雅彦; 山口 瑛子; 小暮 敏博*; 矢内 純太*

日本土壌肥料学雑誌, 94(5), p.376 - 384, 2023/10

土壌のセシウム(Cs)吸着能の定量指標としてRadiocesium interception potential (RIP)が広く用いられてきたが、このRIPが実環境でのCsの分配係数($$K$$$$_{rm d}$$)と必ずしも相関しないことがわかってきた。この原因を明らかにするため、より実環境に則した溶液を用いた$$K$$$$_{rm d}$$測定やRIPとの比較、鉱物の構造評価を行った。その結果、カリウムイオンやアンモニウムイオンなどの競合陽イオンの濃度が重要であることや、鉱物自体の構造変化が重要であることがわかった。

論文

Atomic reconstruction induced by uniaxial stress in MnP

小澤 竜也*; 藤原 理賀; 内原 猛*; 満田 節生*; 矢野 真一郎*; 玉造 博夢; 宗像 孝司*; 中尾 朗子*

Scientific Reports (Internet), 13, p.13750_1 - 13750_8, 2023/08

圧力は、電子状態と原子配列の両方に作用し、物性を劇的に変化させる可能性を持つ。リン化マンガンMnPでは、約8GPaの等方圧力下において、Mn化合物で初めて、超伝導状態が観測された。本研究では、一軸応力がMnPの磁性および結晶構造に及ぼす影響を調査した。磁化測定と中性子回折実験により、0.04GPaという極めて低い一軸応力で、不可逆的な磁化応答が観測され、同時に、MnP型構造に特有の擬回転対称性を満たす結晶ドメインが誘起されることがわかった。不可逆的な磁化応答は、誘起された新たなドメインの構造により説明できることが判明した。一軸応力によって誘起される結晶ドメインに関する研究は過去に例がなく、我々はこの新現象を「原子再構成(AR)」と名付けることとした。我々は、AR現象に対する理解の深化は、誘電性、弾性、電気伝導、磁性、超伝導を含む物質の異方性を制御する結晶ドメイン工学の創出につながると期待している。

論文

Magnetic ordering and structural phase transitions of Nd$$_{3}$$$$T$$$$_{4}$$Sn$$_{13}$$ ($$T$$ = Rh and Ir)

下田 愛海*; 岩佐 和晃*; 桑原 慶太郎*; 佐賀山 基*; 中尾 裕則*; 石角 元志*; 大原 高志; 中尾 朗子*; 星川 晃範*; 石垣 徹*

JPS Conference Proceedings (Internet), 38, p.011091_1 - 011091_6, 2023/05

Synchrotron X-ray diffraction study revealed that Nd$$_{3}$$$$T$$$$_{4}$$Sn$$_{13}$$ ($$T$$ = Rh and Ir) undergo structural phase transitions characterized by the wave vector $$q$$$$_{rm L}$$=(1/2,1/2,0). Neutron diffraction study revealed antiferromagnetic ordering below $$T$$$$_{rm N}$$ = 1.65 and 1.42 K for Nd$$_{3}$$Rh$$_{4}$$Sn$$_{13}$$ and Nd$$_{3}$$Ir$$_{4}$$Sn$$_{13}$$, respectively, which is similar to that previously reported for Nd$$_{3}$$Co$$_{4}$$Sn$$_{13}$$. These compounds show a magnetic susceptibility saturation behavior below approximately 3 K. The results indicate emergence of anomalous electronic correlation in Nd$$_{3}$$$$T$$$$_{4}$$Sn$$_{13}$$ ($$T$$ = Co, Rh, and Ir) above $$T$$$$_{rm N}$$.

論文

Cycloidal magnetic ordering in noncentrosymmetric EuIrGe$$_3$$

松村 武*; 塚越 舜*; 上田 祥央*; 比嘉 野乃花*; 中尾 朗子*; 金子 耕士; 垣花 将司*; 辺土 正人*; 仲間 隆男*; 大貫 惇睦*

Journal of the Physical Society of Japan, 91(7), p.073703_1 - 073703_5, 2022/07

 被引用回数:3 パーセンタイル:81.82(Physics, Multidisciplinary)

Successive magnetic phase transitions in EuIrGe$$_3$$, an intermetallic compound with a body centered tetragonal lattice belonging to a polar space group I4mm, has been investigated by neutron diffraction and resonant X-ray diffraction. It is shown that EuIrGe$$_3$$ exhibits an incommensurate longitudinal sinusoidalorder with $$q{sim}$$ (0, 0, 0.792) and m$$_q{parallel}$$ c-axis in the high temperature phase, which changes to a cycloidal order with $$q$$ = ($${delta}'$$, 0, 0.8) ($${delta}'{sim}$$ 0.017) and m$$_q{parallel}$$ ac-plane in the intermediate phase. In the low temperature phase, the cycloidal plane rotates by 45$$^{circ}$$ to have $$q$$=($${delta}, {delta}$$, 0.8) ($${delta}{sim}$$0.012). It is also pointed out that the X-ray scattering amplitude from odd-parity magnetic quadrupole due to the polar environment interfere with that from normal even-parity magnetic dipole in the magnetic ordered phase.

論文

Magnetic phase diagram of helimagnetic Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$ (0 $$leq$$ x $$leq$$ 0.2) hexagonal ferrite

丸山 建一*; 田中 誠也*; 鬼柳 亮嗣; 中尾 朗子*; 森山 健太郎*; 石川 喜久*; 天児 寧*; 飯山 拓*; 二村 竜祐*; 内海 重宣*; et al.

Journal of Alloys and Compounds, 892, p.162125_1 - 162125_8, 2022/02

 被引用回数:2 パーセンタイル:18.56(Chemistry, Physical)

Hexagonal ferrite Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$ is an important magnetic oxide material in both science and engineering because it exhibits helimagnetism around room temperature (300 K). In this study, the magnetic phase diagram of Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$ consisting of ferri-, heli-, antiferro-, and paramagnetic phases has been completed through magnetization and neutron diffraction measurements. The magnetic phase transition temperature to paramagnetism decreases with the increase in x, and the temperature at which the magnetization reaches a maximum, which corresponds to the magnetic phase transition from heli- to ferrimagnetism, is determined for low x crystals. The temperatures at which helimagnetism appears are precisely determined by observing the magnetic satellite reflection peaks in neutron diffraction at various temperatures, which characterize helimagnetism. Based on these results, the magnetic phase diagram of the Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$ system is constructed in the T-x plane. Helimagnetism appears at x $$>$$ 0.06, and magnetism with antiferromagnetic components appears as the extension phase of helimagnetism at x $$>$$ 0.19 through the coexistence region. The turn angle $$phi_{0}$$ of the helix for each x crystal is calculated from the relationship, $$phi_{0} = 2pidelta$$, where $$delta$$ is the incommensurability. The turn angle $$phi_{0}$$ decreases with the increase in temperature for the same x crystal, and increases with the increase in x at the same temperature. Furthermore, it is found that there are clear thresholds at which $$phi_{0}$$ cannot take values between 0$$^{circ}$$ < $$phi_{0}$$ < 90$$^{circ}$$ and 170$$^{circ}$$ < $$phi_{0}$$ < 180$$^{circ}$$.

論文

Charge-density-wave order and multiple magnetic transitions in divalent europium compound EuAl$$_4$$

金子 耕士; 川崎 卓郎; 仲村 愛*; 宗像 孝司*; 中尾 朗子*; 花島 隆泰*; 鬼柳 亮嗣; 大原 高志; 辺土 正人*; 仲間 隆男*; et al.

Journal of the Physical Society of Japan, 90(6), p.064704_1 - 064704_6, 2021/06

 被引用回数:28 パーセンタイル:96.06(Physics, Multidisciplinary)

Multiple transition phenomena in divalent Eu compound EuAl$$_4$$ with the tetragonal structure were investigated via single crystal time-of-flight neutron Laue technique. At 30 K below a charge-density-wave (CDW) transition, superlattice peaks emerge near nuclear Bragg peaks described by an ordering vector $$q_{rm CDW}$$ = (0 0 $${delta}_c$$). In contrast, magnetic peaks appear at $$q_2 = ({delta}_2 {delta}_2 0)$$ with $${delta}_2$$ = 0.09 below $$T_{N1}$$ = 15.4 K, and moves to $$q_1 = ({delta}_1 0 0)$$ with $${delta}_1$$ = 0.19 below $$T_{N3}$$ =12.2 K, whereas no distinct change in the magnetic Bragg peak was detected at $$T_{N2}$$ and $$T_{N4}$$. The structural modification with $$q_{rm CDW}$$ is characterized by an absence of the superlattice peak in (0 0 $$l$$). Considering an absence of splitting in magnetic peaks along $$l$$, the structural transition is mainly ascribed to a displacement of Al ions within the tetragonal $$ab$$-plane. Complex incommensurate magnetic transitions are in stark contrast to a simple collinear commensurate structure in isovalent EuGa$$_4$$. This could stem from incompatible electronic structures with the CDW transition between two compounds.

論文

Programmable synthesis of silver wheels

Kwon, H.*; Pietrasiak, E.*; 大原 高志; 中尾 朗子*; Chae, B.*; Hwang, C.-C.*; Jung, D.*; Hwang, I.-C.*; Ko, Y. H.*; Kim, K.*; et al.

Inorganic Chemistry, 60(9), p.6403 - 6409, 2021/05

 被引用回数:0 パーセンタイル:0.01(Chemistry, Inorganic & Nuclear)

The synthesis of sandwich-shaped multinuclear silver complexes with planar penta- and tetranuclear wheel-shaped silver units and a central anion is reported, along with complete spectroscopic and structural characterization. An NMR mechanistic study reveals that silver complexes were formed in the following order: 2Ag $$rightarrow$$ 3Ag$$^{rm H2O}$$ $$rightarrow$$ 5Ag$$^{rm OH}$$ $$rightarrow$$ 4Ag$$^{rm OH}$$. The central hydroxides in 4Ag$$^{rm OH}$$ and 5Ag$$^{rm OH}$$ exhibit exotic physical properties due to the confined environment inside the complex. The size of these silver wheels can be tuned by changing the central anion or extracting/adding one silver atom. This study provides the facile way to synthesize discrete wheel-shaped multinuclear silver complexes and provides valuable insights into the dynamics of the self-assembly process.

論文

Correlated Li-ion migration in the superionic conductor Li$$_{10}$$GeP$$_{2}$$S$$_{12}$$

矢島 健*; 日沼 洋陽*; 堀 智*; 岩崎 類*; 菅野 了次*; 大原 高志; 中尾 朗子*; 宗像 孝司*; 廣井 善二*

Journal of Materials Chemistry A, 9(18), p.11278 - 11284, 2021/05

 被引用回数:15 パーセンタイル:82.63(Chemistry, Physical)

Herein, we studied the crystalline compound Li$$_{10}$$GeP$$_{2}$$S$$_{12}$$ with the largest Li-ion conductivity thus far via a novel route based on a combination of single-crystal neutron diffraction experiments at low temperature and first-principles calculations, and found that a correlated migration of the densely packed Li ions governs the overall Li-ion conduction. The correlated migration mechanism provides us with guidelines on how to design efficient superionic conductors for more efficient batteries.

論文

Quantitative evaluation of effects of isomorphic substitutions on delamination energies of clay minerals

山口 瑛子; 浅野 育美*; 北川 結理*; Meng, C.*; 中尾 淳*; 奥村 雅彦

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.127 - 130, 2020/10

粘土鉱物は身近な鉱物の一つであり、環境中の元素挙動に大きな影響を及ぼすにも関わらず、未解明な点が多い。粘土鉱物の重要な特性の一つに、同程度の大きさのイオンによる置換反応(同形置換)があり、粘土鉱物の強い吸着力の要因の一つと考えられているが、実際にどの程度影響を及ぼすか評価されたことはない。本発表では、系統的なモデル作成と第一原理計算を用いることで、同形置換が剥離強度に与える影響を数値的に評価した結果を報告する。

論文

Flux growth and magnetic properties of helimagnetic hexagonal ferrite Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$ single crystals

内海 重宣*; 田中 誠也*; 丸山 建一*; 天児 寧*; 鬼柳 亮嗣; 中尾 朗子*; 森山 健太郎*; 石川 喜久*; 他9名*

ACS Omega (Internet), 5(38), p.24890 - 24897, 2020/09

 被引用回数:4 パーセンタイル:22.5(Chemistry, Multidisciplinary)

六方晶フェライトBa(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$の磁気構造を解明し、さらなる応用開発を進めるためには、大型の高品質な単結晶を育成することが重要な第一歩である。本研究では、Na$$_{2}$$O-Fe$$_{2}$$O$$_{3}$$フラックスを使用した自発結晶化法によって、さまざまなSc濃度$$x$$のBa(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$単結晶の育成に成功した。得られた結晶は、高品質の単相Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$であることがX線回折と元素分析により確認され、$$x$$ = 0.128結晶の77Kの磁化測定では、ヘリマグネティックな挙動を示すことがわかった。$$x$$=0.128結晶の中性子回折測定の結果、211K以下で磁気衛星反射が確認され、Ba(Fe$$_{1-x}$$Sc$$_{x}$$)$$_{12}$$O$$_{19}$$がヘリ磁性物質であることが確認された。

論文

$$q$$=0 long-range magnetic order in centennialite CaCu$$_{3}$$(OD)$$_{6}$$Cl$$_{2}$$ $$cdot$$ 0.6D$$_{2}$$O; A Spin-$$frac{1}{2}$$ perfect kagome antiferromagnet with $$J_{1}$$-$$J_{2}$$-$$J_{d}$$

飯田 一樹*; 吉田 紘行*; 中尾 朗子*; Jeschke, H. O.*; Iqbal, Y.*; 中島 健次; 河村 聖子; 宗像 孝司*; 稲村 泰弘; 村井 直樹; et al.

Physical Review B, 101(22), p.220408_1 - 220408_6, 2020/06

 被引用回数:19 パーセンタイル:79.26(Materials Science, Multidisciplinary)

鉱物センテニアライトCaCu$$_{3}$$(OD)$$_{6}$$Cl$$_{2}$$ $$cdot$$ 0.6D$$_{2}$$Oの結晶構造と磁気構造をシンクロトロンX線回折と中性子回折測定に密度汎関数理論(DFT)と疑似フェルミオン汎関数繰り込み群(PFFRG)の計算を組み合わせることで調べた。CaCu$$_{3}$$(OD)$$_{6}$$Cl$$_{2}$$ $$cdot$$ 0.6D$$_{2}$$OではCu$$^{2+}$$イオンは反強磁性$$J_{1}$$と幾何学的に完全なカゴメネットワークを形成する。Cu$$^{2+}$$とCa$$^{2+}$$イオン間のサイト間無秩序は見つからなかった。CaCu$$_{3}$$(OD)$$_{6}$$Cl$$_{2}$$ $$cdot$$ 0.6D$$_{2}$$Oは$$T$$$$_{rm N}$$=7.2K以下で磁気秩序を示し、負のベクトルスピンキラリティーを持つ$$q$$=0の磁気構造が現れる。0.3Kでの秩序モーメントは0.58(2)$$mu$$Bに抑えられている。我々のDFT計算では、この系が量子臨界点の近くにあり、$$J_{1}$$-$$J_{2}$$-$$J_{d}$$カゴメ反強磁性体の優れた実現であることを示唆している。

論文

High-field depinned phase and planar Hall effect in the skyrmion host Gd$$_2$$PdSi$$_3$$

Hirschberger, M.*; 中島 多朗*; Kriener, M.*; 車地 崇*; Spitz, L.*; Gao, S.*; 吉川 明子*; 山崎 裕一*; 佐賀山 基*; 中尾 裕則*; et al.

Physical Review B, 101(22), p.220401_1 - 220401_6, 2020/06

 被引用回数:35 パーセンタイル:92.14(Materials Science, Multidisciplinary)

For the skyrmion-hosting intermetallic Gd$$_2$$PdSi$$_3$$ with centrosymmetric hexagonal lattice and triangular net of rare earth sites, we report a thorough investigation of the magnetic phase diagram. Our work reveals a magnetic phase with an isotropic value of the critical field for all orientations, where the magnetic ordering vector ${bf q}$ is depinned from its preferred directions in the basal plane. The bulk nature of the skyrmion lattice and of other magnetic phases was evidenced by specific-heat measurements. Resistivity anisotropy, likely originating from partial gapping of the density of states along ${bf q}$ in this Ruderman-Kittel-Kasuya-Yoshida magnet, is picked up via the planar Hall effect (PHE). The PHE confirms the single-${bf q}$ nature of the magnetic order when the field is in the hexagonal plane, and allows one to detect the preferred directions of ${bf q}$. Several scenarios for the depinned phase are discussed on the basis of the data.

論文

Magnetically induced electric polarization in Ba$$_{3}$$Fe$$_{2}$$O$$_{5}$$Cl$$_{2}$$ with tunable direction in three dimensions

阿部 伸行*; 塩澤 俊介*; 松浦 慧介*; 佐賀山 基*; 中尾 朗子*; 大原 高志; 徳永 祐介*; 有馬 孝尚*

Physical Review B, 101(18), p.180407_1 - 180407_5, 2020/05

 被引用回数:2 パーセンタイル:13.75(Materials Science, Multidisciplinary)

The correlation between magnetism and electric polarization in a chiral insulating magnet Ba$$_{3}$$Fe$$_{2}$$O$$_{5}$$Cl$$_{2}$$ has been investigated. The temperature dependence of magnetic susceptibility shows an anomaly at 564 K, suggesting the onset of antiferromagnetic order of Fe$$^{3+}$$ moments. Electric polarization appears in a magnetic field below TN due to the spin-direction-dependent metal-ligand hybridization. The direction of the electric polarization can be controlled in three-dimensional space by changing the direction of an external magnetic field. This compound also shows an antiferromagnetic-to-weak-ferromagnetic transition accompanied by a structural phase transition at 140 K.

論文

Successive phase transitions in $$R_{3}$$Ir$$_{4}$$Sn$$_{13}$$ ($$R$$: La and Ce) investigated using neutron and X-ray diffraction

中里 晟也*; 岩佐 和晃*; 橋本 大輔*; 塩澤 真未*; 桑原 慶太郎*; 中尾 裕則*; 佐賀山 基*; 石角 元志*; 大原 高志; 中尾 朗子*; et al.

JPS Conference Proceedings (Internet), 30, p.011128_1 - 011128_6, 2020/03

Successive phase transitions of $$R_{3}$$Ir$$_{4}$$Sn$$_{13}$$ ($$R$$: La and Ce) were studied using neutron and X-ray diffraction techniques. A semimetal Ce$$_{3}$$Ir$$_{4}$$Sn$$_{13}$$ undergoes three phase transitions: an antiferromagnetic ordering characterized by a propagation vector $$q_{rm M}$$ = (1/2, 1/2, 2/5) below 0.6 K, a structural transformation with $$q_{rm S2}$$= (1/4, 1/4, 1/4) at 2.0 K, and another structural transformation with $$q_{rm S1}$$ = (1/2, 1/2, 0) above room temperature. La$$_{3}$$Ir$$_{4}$$Sn$$_{13}$$ was confirmed to be a superconductor below 2.5 K under the $$q_{rm S1}$$ = (1/2, 1/2, 0) structure that also appears above room temperature.

論文

Multi-step magnetic transitions in EuNiIn$$_4$$

池田 修悟*; 金子 耕士; 田中 佑季*; 川崎 卓郎; 花島 隆泰*; 宗像 孝司*; 中尾 朗子*; 鬼柳 亮嗣; 大原 高志; 望月 健生*; et al.

Journal of the Physical Society of Japan, 89(1), p.014707_1 - 014707_7, 2020/01

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

Magnetism in EuNiIn$$_4$$ has been studied by specific heat, magnetic susceptibility, magnetization, $$^{151}$$Eu M$"o$ssbauer spectroscopy, and neutron diffraction experiments. The specific heat shows two magnetic transitions at $$T_{rm N1}$$ and $$T_{rm N2}$$ at zero magnetic field. An antiferromagnetic ground state of EuNiIn$$_4$$ has a uniaxial magnetic anisotropy along the b-axis, revealed by the magnetic susceptibility and the M$"o$ssbauer spectroscopy. Single crystal neutron diffraction experiments clarify that this antiferromagnetic structure in the ground state is characterized by the commensurate propagation vector $$q$$ = (1/2, 1/2, 1/2) which reveals no distinct anomaly at $$T_{rm N2}$$. The magnetization curve along the b-axis at 2 K shows four successive magnetic field-induced transitions up to 50 kOe and, reaches 7 $${mu}_{rm B}$$/f.u. above 190 kOe, The magnetic phase diagram in EuNiIn$$_4$$ has unique characteristics with five magnetic states in low magnetic field.

論文

Coexisting spin resonance and long-range magnetic order of Eu in EuRbFe$$_{4}$$As$$_{4}$$

飯田 一樹*; 永井 佑紀; 石田 茂之*; 石角 元志*; 村井 直樹; Christianson, A. D.*; 吉田 紘行*; 稲村 泰弘; 中村 博樹; 中尾 朗子*; et al.

Physical Review B, 100(1), p.014506_1 - 014506_8, 2019/07

 被引用回数:29 パーセンタイル:84.95(Materials Science, Multidisciplinary)

パルス中性子散乱実験による鉄系超伝導体EuRbFe$$_{4}$$As$$_{4}$$のスピン揺らぎ、磁気構造の測定を行い、同物質における超伝導体対称性などの議論を行った。

論文

Magnetic, thermal, and neutron diffraction studies of a coordination polymer; bis(glycolato)cobalt(II)

中根 僚宏*; 米山 翔太*; 兒玉 健*; 菊地 耕一*; 中尾 朗子*; 大原 高志; 東中 隆二*; 松田 達磨*; 青木 勇二*; 藤田 渉*

Dalton Transactions (Internet), 48(1), p.333 - 338, 2019/01

 被引用回数:2 パーセンタイル:11.89(Chemistry, Inorganic & Nuclear)

The two-dimensional quadratic lattice magnet, bis(glycolato)cobalt(II) ([Co(HOCH$$_{2}$$CO$$_{2}$$)$$_{2}$$]), showed anti-ferromagnetic ordering at 15.0 K and an abrupt increase in magnetisation at H = 22 600 Oe and 2 K, thereby acting as a metamagnet. Neutron diffraction studies suggested that the magnetic moment vectors of the Co(II) ions had an amplitude of 3.59 mB and were not aligned in a fully antiparallel fashion to those of their neighbours, which caused canting between the magnetic moment vectors in the sheet. The canting angle was determined to be 7.1deg. Canting induced net magnetisation in the sheet, but this magnetisation was cancelled between sheets. The magnetisations in the sheets were oriented parallel to the magnetic field at the critical magnetic field.

論文

Unique helical magnetic order and field-induced phase in trillium lattice antiferromagnet EuPtSi

金子 耕士; Frontzek, M. D.*; 松田 雅昌*; 中尾 朗子*; 宗像 孝司*; 大原 高志; 垣花 将司*; 芳賀 芳範; 辺土 正人*; 仲間 隆男*; et al.

Journal of the Physical Society of Japan, 88, p.013702_1 - 013702_5, 2019/01

 被引用回数:56 パーセンタイル:95.14(Physics, Multidisciplinary)

Magnetic transitions in chiral antiferromagnet EuPtSi were investigated by means of single crystal neutron diffraction. In the ground state, magnetic peaks emerge at positions represented by $$q_{1}$$=$$(0.2, 0.3, 0)$$. Upon heating, an additional magnetic peak splitting around 2.5 K was uncovered, indicating a presence of a first-order transition with $$q^*_{1}$$=$$(0.2, 0.3, {delta})$$. An half-polarized neutron scattering for polarization parallel to Q reveled that polarization antiparallel to Q has stronger intensity in both magnetic phases. This feature clarifies single chiral character of helical structure with moments normal to the ordering vector in both ordered states. Under vertical magnetic field along [1,1,1] in the $$A$$ phase, magnetic peaks form hexagonal patterns in the equatorial scattering plane around nuclear. An ordering vector $$q_{A}$$ of the $$A$$-phase has the similar size in the periodicity to $$q_{1}$$, and could be a hallmark of a formation of skyrmion lattice in EuPtSi.

論文

Magnetic-ordering propagation vectors of terbium hexaboride revisited

岩佐 和晃*; 伊賀 文俊*; 茂吉 武人*; 中尾 朗子*; 大原 高志

Journal of the Physical Society of Japan, 87(6), p.064705_1 - 064705_5, 2018/06

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

The magnetic-ordered state of a single-crystal sample of TbB$$_{6}$$ has been studied with the high-precision neutron diffraction instrument SENJU installed at BL18 of the Materials and Life Science Facility in J-PARC. We observed new Bragg-reflection spots characterized by a propagation vector $$q_{rm M2}$$ = (1/4, 1/4, 0) below the N$'e$el temperature $$T_{rm N}$$ $$approx$$ 20 K, in addition to the $$q_{rm M1}$$ = (1/4, 1/4. 1/2) reported in the previous literatures. Because X-ray Thomson scattering measurements do not detect the $$q_{rm M2}$$ superlattice reflections at 13 K, $$q_{rm M2}$$ is a new magnetic-ordering propagation vector. The magnetic multi-q structure of TbB$$_{6}$$ is similar to that of CeB$$_{6}$$, whereas the ratio of the $$q_{rm M2}$$ amplitude to that of qM1 is smaller than in CeB$$_{6}$$. The combination of $$q_{rm M1}$$ and $$q_{rm M2}$$ is expected to assist the $$q_{rm L1}$$ = (1/2, 0, 0) lattice modulation.

論文

Mn$$_{2}$$VAl Heusler alloy thin films; Appearance of antiferromagnetism and exchange bias in a layered structure with Fe

土屋 朋生*; 小林 亮太*; 窪田 崇秀*; 斉藤 耕太郎*; 小野 寛太*; 大原 高志; 中尾 朗子*; 高梨 弘毅*

Journal of Physics D; Applied Physics, 51(6), p.065001_1 - 065001_7, 2018/02

 被引用回数:8 パーセンタイル:46.95(Physics, Applied)

Mn$$_{2}$$VAl Heusler alloy films were epitaxially grown on MgO(100) single-crystal substrates by ultra-high-vacuum magnetron sputtering. A2- and L21-type Mn$$_{2}$$VAl order was controlled by the deposition temperature. A2-type Mn$$_{2}$$VAl films showed no spontaneous magnetization, while L21-type Mn$$_{2}$$VAl films showed ferrimagnetic behaviour with a maximum saturation magnetization of 220 emu/cm$$^{3}$$ at room temperature (RT). An antiferromagnetic reflection was observed with neutron diffraction at RT for an A2-type Mn$$_{2}$$VAl film deposited at 400$$^{circ}$$C. A bilayer sample of the antiferromagnetic A2-type Mn$$_{2}$$VAl and Fe showed an exchange bias of 120 Oe at 10 K.

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