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論文

Polarization dependence of soft X-ray absorption spectroscopy on the heavy fermion superconductor CeNi $_{2}$ Ge $_{2}$

藤原秀紀*; 中谷泰博*; 荒谷秀和*; 金井惟奈*; 山神光平*; 濱本諭*; 木須孝幸*; 関山明*; 田中新*; 海老原孝雄*; et al.

New Physics; Sae Mulli, 73(12), p.1062 - 1066, 2023/12

https://doi.org/10.3938/NPSM.73.1062

We have performed soft X-ray absorption spectroscopy (XAS) on the heavy fermion superconductor CeNi $_{2}$ Ge $_{2}$ to examine the local 4 electronic structure. The XAS spectra are qualitatively explained by ionic calculations, indicating a degree of localized character of the 4 states, while sizable -hybridization effects are also observed in the XAS spectra and those magnetic circular dichroism. In addition, the temperature dependence of linear dichroism in the XAS spectra indicates that the ground state symmetry is $_{7}$ , and the excited states with $_{6}$ symmetry is above 390 K.

論文

Impact of the ground-state 4 symmetry for anisotropic hybridization in the heavy-fermion superconductor CeNi $_{2}$ Ge $_{2}$

藤原秀紀*; 中谷泰博*; 荒谷秀和*; 金井惟奈*; 山神光平*; 濱本諭*; 木須孝幸*; 山崎篤志*; 東谷篤志*; 今田真*; et al.

Physical Review B, 108(16), p.165121_1 - 165121_10, 2023/10

https://doi.org/10.1103/PhysRevB.108.165121

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

We report the ground-state symmetry of the Ce 4 states in the heavy-fermion superconductor CeNi $_{2}$ Ge $_{2}$ , yielding anisotropic hybridization between the Ce 4 states and conducting electrons. By analyzing linear dichroism in soft X-ray absorption and core-level hard X-ray photoemission spectra, the 4 symmetry is determined as -type $_{7}$ , promoting predominant hybridization with the conducting electrons originating from the Ge site. The band structures probed by soft X-ray angle-resolved photoemission indicates that the Ge 4 components contribute to the band renormalization through the anisotropic hybridization effects, suggesting that the control of the electronic structures of Ge orbital gives an impact to achieve the exotic phenomena in CeNi $_{2}$ Ge $_{2}$ .

論文

Sodium-cooled Fast Reactors

大島宏之; 森下正樹*; 相澤康介; 安藤勝訓; 芦田貴志; 近澤佳隆; 堂田哲広; 江沼康弘; 江連俊樹; 深野義隆; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

https://shop.elsevier.com/books/sodium-cooled-fast-reactors/morishita/978-0-12-824076-2

ナトリウム冷却高速炉(SFR: Sodium-cooled Fast Reactor)の歴史や、利点、課題を踏まえた安全性、設計、運用、メンテナンスなどについて解説する。AIを利用した設計手法など、SFRの実用化に向けた設計や研究開発についても述べる。

論文

Magnetoelastic anisotropy in Heusler-type Mn $_{2-delta}$ CoGa $_{1+delta}$ films

窪田崇秀*; 高野大地*; 小田洋平*; Mohanty, S.*; 伊藤啓太*; 松木充弘*; 林田誠弘*; Sun, M.*; 竹田幸治; 斎藤祐児; et al.

Physical Review Materials (Internet), 6(4), p.044405_1 - 044405_12, 2022/04

https://doi.org/10.1103/PhysRevMaterials.6.044405

被引用回数：5 パーセンタイル：59.75(Materials Science, Multidisciplinary)

This study focuses on an inverse-type Heusler alloy, Mn $_{2-delta}$ CoGa $_{1+delta}$ (MCG), with a small off-stoichiometry (), showing perpendicular magnetic anisotropy (PMA). We observed a relatively large uniaxial magnetocrystalline anisotropy constant ( $K_mathrm{u}$ ) on the order of 10 J/m at room temperature in the MCG films with a small tetragonal distortion of a few percent. X-ray magnetic circular dichroism (XMCD) was employed to get insight into the origin for the PMA. Negligible angular variation of the orbital magnetic moment evaluated using the XMCD spectra suggested a minor role of the so-called Bruno's term to $K_mathrm{u}$ . The origin of the PMA was discussed based on the second-order perturbation theory in terms of the spin-orbit coupling, and first principles calculations, claiming that the mixing of the occupied - and the unoccupied -spin states is responsible for the PMA of the MCG films.

論文

Mn L $_{2,3}$ -edge EXAFS and magnetic EXAFS studies on the halfmetallic ferromagnet Co $_{2}$ MnSi

向後純也*; 藤原秀紀*; 関山明*; 斎藤祐児; 梅津理恵*; 二木かおり*

Journal of the Physical Society of Japan, 91(3), p.034702_1 - 034702_12, 2022/03

https://doi.org/10.7566/JPSJ.91.034702

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

We report magnetic circular dichroism in extended X-ray absorption fine structure (EXAFS) in a prototypical halfmetallic ferromagnet, Co $_{2}$ MnSi. The EXAFS oscillations at the Mn L $_{2,3}$ edges are analyzed to obtain parameters used in the analysis of the magnetic EXAFS (MEXAFS). Theoretical calculations of MEXAFS spectra in Co $_{2}$ MnSi show that the linear-path scatterings have larger contributions than the multiple triangular-path scatterings. Furthermore, the period of the oscillations in the MEXAFS spectra is shorter than that in the EXAFS spectra indicating that the far site contributions from the second to the fourth nearest neighbor Co and the third nearest Si atoms can strongly influence the MEXAFS oscillations, while the Mn atoms, despite the large magnetic moment, can have little contributions due to the interference of the spin components.

論文

Structures of magnetic excitations in the spin- $frac{1}{2}$ kagome-lattice antiferromagnets Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ and Rb $_{2}$ Cu $_{3}$ SnF $_{12}$

齋藤睦己*; 高岸龍之介*; 栗田伸之*; 渡邊正理*; 田中秀数*; 野村竜司*; 福元好志*; 池内和彦*; 梶本亮一

Physical Review B, 105(6), p.064424_1 - 064424_15, 2022/02

https://doi.org/10.1103/PhysRevB.105.064424

被引用回数：6 パーセンタイル：73.14(Materials Science, Multidisciplinary)

Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ is a spin- $frac{1}{2}$ antiferromagnet on a nearly uniform kagome lattice. This compound undergoes magnetic ordering with the = 0 structure and positive chirality, which is mainly caused by the large Dzyaloshinskii-Moriya interaction. Rb $_{2}$ Cu $_{3}$ SnF $_{12}$ is a spin- $frac{1}{2}$ antiferromagnet on a modified kagome lattice with a enlarged chemical unit cell at room temperature. Its ground state is a pinwheel valence bond solid (VBS) with an excitation gap. Here, we show the structures of magnetic excitations in Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ and Rb $_{2}$ Cu $_{3}$ SnF $_{12}$ investigated by inelastic neutron scattering in wide energy and momentum ranges. For Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ , four single-magnon excitation modes were observed. It was confirmed that the energy of single-magnon excitations arising from the point in the extended Brillouin zones is largely renormalized downwards. It was found that the broad excitation continuum without a marked structure spreads in a wide energy range from to approximately . These findings strongly suggest spinon excitations as elementary excitations in Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ . In Rb $_{2}$ Cu $_{3}$ SnF $_{12}$ , singlet-triplet excitations from the pinwheel VBS state and their ghost modes caused by the enlargement of the chemical unit cell were clearly confirmed. It was found that the excitation continuum is structured in the low-energy region approximately below $J_mathrm{avg}$ and the almost structureless high-energy excitation continuum extends to approximately $2.6J_mathrm{avg}$ . The characteristics of the high-energy excitation continuum are common to both Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ and Rb $_{2}$ Cu $_{3}$ SnF $_{12}$ , irrespective of their ground states. The experimental results strongly suggest that the spin liquid component remains in the ground state as quantum fluctuations in Cs $_{2}$ Cu $_{3}$ SnF $_{12}$ and Rb $_{2}$ Cu $_{3}$ SnF $_{12}$ .

論文

Extraction behavior of a novel functionalized ionic liquid for separation of platinum group metals from aqueous nitric acid solution

伊藤辰也; 大杉遥*; 大沢直樹*; 高橋正幸*; Kim, S.-Y.*; 永石隆二

Analytical Sciences, 38(1), p.91 - 97, 2022/01

https://doi.org/10.2116/analsci.21P057

被引用回数：2 パーセンタイル：15.48(Chemistry, Analytical)

高レベル放射性廃液(HLLW)などの硝酸水溶液から白金族元素(Ru, Rh, Pd)を効果的かつ効率的に抽出するために、ソフトなSドナーを含有するチオジグリコールアミド酸を修飾した新規イオン液体(IL)を合成した。このILは約100%の抽出率で迅速なPd(II)の抽出を可能にした。Ru(III)及びRh(III)の抽出は、Pd(II)より遅いものの、温度上昇によって抽出速度が加速した。50 $^{circ}$ CにおけるRu(III)とRh(III)の抽出はそれぞれ4hと8h以内に平衡に達し、抽出系に補助剤やその他の方法を使用しなくても抽出率は90%を超えた。さらに、このILは50 $^{circ}$ Cにおいて2h以内に模擬HLLWから90%以上のRu(III)、Rh(III)及びPd(II)を抽出可能だった。

論文

Sm valence determination of Sm-based intermetallics using $^{149}$ Sm Mssbauer and Sm L $_{rm III}$ -edge X-ray absorption spectroscopies

筒井智嗣; 東中隆二*; 中村頼人*; 藤原孝将*; 中村仁*; 小林義男*; 伊藤孝; 依田芳卓*; 加藤和男*; 新田清文*; et al.

Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12

https://doi.org/10.1007/s10751-021-01759-x

被引用回数：1 パーセンタイル：84.42(Physics, Atomic, Molecular & Chemical)

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy was performed in Sm-based intermetallics having a cubic crystal structure, Sm $_{3}Tr_{4}$ Ge $_{13}$ , SmB $_{6}$ , SmBe $_{13}$ , and Sm $Tr_{2}$ Al $_{20}$ ( = transition metals). In spite of the difference of the local structure around the Sm sites, the observed Mssbauer spectra consist of a single line at 300 K. On the other hand, Sm L $_{rm III}$ -edge X-ray absorption spectra consist of two components, suggesting Sm $^{2+}$ and Sm $^{3+}$ states. Difference of the number of the spectral components between the Mssbauer spectroscopy and X-ray absorption spectroscopy is caused by the difference of the time window in the scattering process of these measurements. Correlation between the isomer shifts in the Mssbauer spectroscopy and average Sm valence states estimated from the X-ray absorption spectroscopy exhibits a linear correlation.

論文

Review of engagement activities to promote awareness of radiation and its associated risk amongst the Japanese public before and after the Fukushima Daiichi Nuclear Power Plant accident

迫田晃弘; 野村直希*; 黒田佑次郎*; 河野恭彦; 内藤航*; 吉田浩子*

Journal of Radiological Protection, 41(4), p.1258 - 1287, 2021/12

https://doi.org/10.1088/1361-6498/ac2678

被引用回数：1 パーセンタイル：13.18(Environmental Sciences)

福島第一原子力発電所の事故後、多くの放射線専門家は、リスクコミュニケーションを含む公衆理解(PU)に関する事故前の認識と実態との間に大きなギャップがあることを経験した。そこで本研究では、放射線や放射線リスクに関する日本の6つの学会(社会的に中立的な専門家コミュニティ)のPU活動について、事故前後の情報を収集・分析した。これらの学会が一般市民に提供している活動について、以下の観点から考察した。(1)リソース、モチベーション、公衆の関心・懸念による双方向のコミュニケーションの難しさ、(2)学術研究とPU活動のバランス、(3)会員専門家の中立性と独立性を確保した、学会の一般市民との信頼関係の構築、(4)一般市民へのエンゲージメントに向けた学会間の議論。放射線防護の専門家や学会が公衆コミュニケーションやアウトリーチにおける役割について、本論文をきっかけに国内外の議論が一層高まることを期待している。

論文

Panel session toward improved communication and engagement with the public after the Fukushima Daiichi Nuclear Power Plant Accident; Study reports and discussion with specialists from relevant fields

吉田浩子*; 黒田佑次郎*; 河野恭彦; 内藤航*; 迫田晃弘

Journal of Radiation Protection and Research, 46(3), p.134 - 142, 2021/09

https://doi.org/10.14407/jrpr.2020.00283

日本保健物理学会では「福島第一原子力発電所事故後のPublic Understandingの取り組みに関する専門研究会(PU専研)」を設置し、2018年度から2年間にわたり、福島事故後に行われてきたPublic Understanding促進のさまざまな取り組みを収集・解析することにより、事故後の信頼が失われた状況における科学の公衆理解のあり方や専門家はどのような心構えや態度で公衆に対応すべきか等について議論を重ねてきた。本稿では、日本保健物理学会第53回研究発表会(WEB大会)で開催された本専門研究会のパネルセッションを概説する。本セッションは、(1)これまでのPU専研の成果報告、(2)指定発言者として招聘した社会学や倫理の専門家からPU専研の成果報告に対するコメント、(3)PU専研のサブグループリーダー3名と指定発言者2名をパネリストとした議論、(4)ラポータによる報告で構成されていた。

論文

Detecting halfmetallic electronic structures of spintronic materials in a magnetic field

藤原秀紀*; 梅津理恵*; 黒田文彬*; 宮脇淳*; 樫内利幸*; 西本幸平*; 永井浩大*; 関山明*; 入澤明典*; 竹田幸治; et al.

Scientific Reports (Internet), 11(1), p.18654_1 - 18654_9, 2021/09

https://doi.org/10.1038/s41598-021-97992-z

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

Band-gap engineering is one of the fundamental techniques in semiconductor technology. To fully utilize the spintronic material, it is essential to optimize the spin-dependent electronic structure in operando conditions by applying the magnetic and/or electric fields. Here we present a new spectroscopic technique to probe the spin-polarized electronic structures by using magnetic circular dichroism (MCD) in resonant inelastic soft X-ray scattering (RIXS) under an external magnetic field. Thanks to the spin-selective dipole-allowed transitions in the RIXS-MCD, we have successfully demonstrated the direct evidence of the perfectly spin-polarized electronic structures for the prototypical halfmetallic Heusller alloy, Co $_{2}$ MnSi. The RIXS-MCD is a promising tool to probe the spin-dependent carriers and band-gap with element specific way induced in buried magnetic layers under operando conditions.

論文

Microstructures and interface magnetic moments in Mn $_{2}$ VAl/Fe layered films showing exchange bias

窪田崇秀*; 嶋田雄介*; 土屋朋生*; 吉川智己*; 伊藤啓太*; 竹田幸治; 斎藤祐児; 今野豊彦*; 木村昭夫*; 高梨弘毅*

Nanomaterials (Internet), 11(7), p.1723_1 - 1723_11, 2021/07

https://doi.org/10.3390/nano11071723

被引用回数：2 パーセンタイル：17.84(Chemistry, Multidisciplinary)

Heusler alloys exhibit various magnetic properties. In this study, a layered sample consisting of a Heusler alloy, Mn $_{2}$ VAl and a ferromagnet, Fe, is selected as a material system exhibiting exchange bias. Although the fully ordered Mn $_{2}$ VAl is known as a ferrimagnet, the Mn $_{2}$ VAl/Fe layered structure exhibits exchange bias. The high-angle annular dark field STEM images demonstrated the formation of Mn $_{2}$ VAl clusters with the L2 $_{1}$ phase distributed only around the interface to the Fe layer in the sample. Furthermore, the antiferromagnetic coupling between the Mn- and Fe-moments were observed in element specific hysteresis loops measured using XMCD. The locally ordered L2 $_{1}$ phase and antiferromagnetic Mn-moments in the Mn $_{2}$ VAl layer are important for the exchange bias.

論文

Solvent extraction of cesium using DtBuDB18C6 into various organic solvents

佐々木祐二; 森田圭介; 北辻章浩; 伊藤圭祐*; 吉塚和治*

Solvent Extraction Research and Development, Japan, 28(2), p.121 - 131, 2021/00

https://doi.org/10.15261/serdj.28.121

被引用回数：2 パーセンタイル：14.88(Chemistry, Multidisciplinary)

Csは高レベル廃液中で分離対象元素の一つである。しかし、Csはアルカリ金属に属し分離が難しい元素である。DtBuDB18C6はCs抽出に有効な化合物であるとされる。しかし、プロセスで用いられる希釈剤(ドデカンやオクタノール)への溶解度が低く、利用しづらく、他の希釈剤を検討した。その結果、ケトン,エーテル,エステル系の溶媒中にDtBuDB18C6の溶解度は高く、また、ケトン,アルコールを用いる場合、Cs分配比は比較的高いことが分かった。それぞれの抽出溶媒を用いて、Csの分配挙動,抽出条件,抽出容量などを検討した。

論文

「福島第一原子力発電所事故後のPublic Understanding(科学の公衆理解)の取り組みに関する専門研究会」のパネルセッション; 活動成果報告及び関連分野からの専門家を交えた議論

吉田浩子*; 黒田佑次郎*; 河野恭彦; 内藤航*; 迫田晃弘

保健物理(インターネット), 55(4), p.257 - 263, 2020/12

https://doi.org/10.5453/jhps.55.257

論文

Direct observation of the magnetic ordering process in the ferromagnetic semiconductor Ga $_{1-x}$ Mn $_{x}$ As via soft X-ray magnetic circular dichroism

竹田幸治; 大矢忍*; Pham, N. H.*; 小林正起*; 斎藤祐児; 山上浩志; 田中雅明*; 藤森淳*

Journal of Applied Physics, 128(21), p.213902_1 - 213902_11, 2020/12

https://doi.org/10.1063/5.0031605

被引用回数：8 パーセンタイル：44.34(Physics, Applied)

In order to understand the mechanism of the ferromagnetism in Ga $_{1-x}$ Mn $_{x}$ As ((Ga,Mn)As), we have investigated the magnetic behavior on a microscopic level through systematic temperature () and magnetic-field () dependent soft X-ray magnetic circular dichroism (XMCD) experiments at the Mn $L_mathrm{2,3}$ absorption edges. The and dependences of XMCD intensities have been analyzed using a model consisting of the ferromagnetic (FM), paramagnetic, and superparamagnetic (SPM) components. Intriguingly, we have found a common behavior for the ferromagnetic ordering process in (Ga,Mn)As samples with different Mn concentrations and different Curie temperature ( $T_mathrm{C}$ ) values. In particular, the SPM component develops well above $T_mathrm{C}$ , indicating that local FM regions are formed well above $T_mathrm{C}$ . The present findings indicate that the onset of ferromagnetic ordering is triggered by local electronic states around the substitutional Mn ions. Insight into the most representative ferromagnetic semiconductor, (Ga,Mn)As, will be an important step in understanding the mechanism of ferromagnetic ordering in various ferromagnetic semiconductor families.

論文

Insight into Kondo screening in the intermediate-valence compound SmOsSb $_{12}$ uncovered by soft X-ray magnetic circular dichroism

斎藤祐児; 藤原秀紀*; 保井晃*; 門野利治*; 菅原仁*; 菊地大輔*; 佐藤英行*; 菅滋正*; 山崎篤志*; 関山明*; et al.

Physical Review B, 102(16), p.165152_1 - 165152_8, 2020/10

https://doi.org/10.1103/PhysRevB.102.165152

被引用回数：1 パーセンタイル：6.04(Materials Science, Multidisciplinary)

Through a high-precision soft X-ray magnetic circular dichroism (XMCD) study of the intermediate-valence compound SmOsSb $_{12}$ , we show our successful approach of revealing unprecedented details of Kondo screening below a characteristic temperature of $T_{0} sim$ 20 K in the paramagnetic phase. The multiplet XMCD structure at the Sm $M_{5}$ edge sensitive to the 4 configuration enabled us to observe a clear difference between the temperature evolution above and below $T_{0}$ with one- and two-component behavior, respectively. Our findings are in strong contrast to the conventional Kondo crossover that coincides with the valence transition, but are qualitatively accounted for by theoretical XMCD predictions combined with the two-fluid phenomenology recently proposed. This work contributes to the large context of Kondo physics that is closely related to quantum criticality in heavy fermion systems.

論文

Examples of practical activities related to public understanding of radiation risk following the Fukushima nuclear accident

内藤航*; 上坂元紀*; 黒田佑次郎*; 河野恭彦; 迫田晃弘; 吉田浩子*

Radioprotection, 55(4), p.297 - 307, 2020/10

https://doi.org/10.1051/radiopro/2020086

被引用回数：7 パーセンタイル：77.21(Environmental Sciences)

日本の福島第一原子力発電所事故後、福島県内外において、放射線リスクの公衆理解に関連した多くの実践的活動が実施された。これまでのところ、それら活動において注目すべきアプローチなどは整理されてこなかった。本研究では、福島原子力事故後の放射線リスクの公衆理解に関連した注目すべき実践的活動を整理し、また主にコミュニケーションのアプローチの観点から議論した。いくつかの事例が示すように、さまざまな形で放射線リスクを文脈化・局在化する取り組みがみられ、これら取り組みは実際の経験を通じて、効果的な公衆理解活動の重要な要素であると確認された。被災した住民や放射能測定する市民のようなコミュニティーベースあるいは市民科学的なアプローチは放射線状況の公衆理解に貢献してきたが、倫理的側面や不確かさの扱いなどでいくつかの課題が明らかになった。情報通信技術の時代において、多くの市民・専門家・機関によって、ソーシャルメディアは放射線リスクに関するメッセージを公衆に伝える大衆的プラットフォームとなり、ソーシャルメディアは放射線リスク情報の提供において重要な役割を担うことが実証された。本研究で議論された実践的活動からの知見や教訓は、事故後の復興期において、放射線リスクだけでなく他の化学物質などのリスクの公衆理解の推進、将来の災害への備え、およびリスクコミュニケーション計画の支援に有用であると考えられる。

論文

Unveiling spin-dependent unoccupied electronic states of Co $_{2}$ MnGe (Ga) film via Ge (Ga) $L_{2,3}$ absorption spectroscopy

吉川智己*; Antonov, V. N.*; 河野嵩*; 鹿子木将明*; 角田一樹; 宮本幸治*; 竹田幸治; 斎藤祐児; 後藤一希*; 桜庭裕弥*; et al.

Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08

https://doi.org/10.1103/PhysRevB.102.064428

被引用回数：2 パーセンタイル：12.9(Materials Science, Multidisciplinary)

X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy were applied at the Ge (Ga) $L_{2,3}$ edge to unravel the spin-resolved unoccupied electronic states of Co $_{2}$ MnGe (Ga). Complicated spectral features were observed in both XAS and XMCD spectra. For their interpretation, we compared the experimental XAS and XMCD spectra with the calculated Ge (Ga) 4 and 4 orbital partial density of states. The comparison enabled a qualitative explanation of the XMCD spectra as the difference between the majority and minority-spin unoccupied density of states summed over the 4 and 4 orbitals. Our finding provides a new approach to uncover the spin-split partial density of states above the Fermi level.

論文

Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi $_{2}$ Te $_{4}$

Shikin, A. M.*; Estyunin, D. A.*; Klimovskikh, I. I.*; Filnov, S. O.*; Kumar, S.*; Schwier, E. F.*; 宮本幸治*; 奥田太一*; 木村昭夫*; 黒田健太*; et al.

Scientific Reports (Internet), 10, p.13226_1 - 13226_13, 2020/08

https://doi.org/10.1038/s41598-020-70089-9

被引用回数：59 パーセンタイル：96.43(Multidisciplinary Sciences)

Modification of the gap at the Dirac point (DP) in axion antiferromagnetic topological insulator MnBi $_{2}$ Te $_{4}$ and its electronic and spin structure have been studied by angle- and spin-resolved photoemission spectroscopy (ARPES) under laser excitation at various temperatures, light polarizations and photon energies. We have distinguished both large and reduced gaps at the DP in the ARPES dispersions, which remain open above the Nel temperature of $T_textrm{N}$ = 24.5 K. We propose that the gap above $T_textrm{N}$ remains open due to a short-range magnetic field generated by chiral spin fluctuations. Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show a surface ferromagnetic ordering for the large gap sample and apparently significantly reduced effective magnetic moment for the reduced gap sample.

論文

Manipulation of saturation magnetization and perpendicular magnetic anisotropy in epitaxial Co $_{x}$ Mn $_{4-x}$ N films with ferrimagnetic compensation

伊藤啓太*; 安富陽子*; Zhu, S.*; Nurmamat, M.*; 田原昌樹*; 都甲薫*; 秋山了太*; 竹田幸治; 斎藤祐児; 小口多美夫*; et al.

Physical Review B, 101(10), p.104401_1 - 104401_8, 2020/03

https://doi.org/10.1103/PhysRevB.101.104401

被引用回数：18 パーセンタイル：73.04(Materials Science, Multidisciplinary)

Spintronics devices utilizing a magnetic domain wall motion have attracted increasing attention, and ferrimagentic materials with almost compensated magnetic moments are highly required to realize the fast magnetic domain wall motion. Here, we report a key function for this purpose in anti-perovskite Co $_{x}$ Mn $_{4-x}$ N films. Perpendicular magnetization emerges for , and the saturation magnetization reaches a minimum value at .