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GeTe
homojunctions小幡 玲二*; 齊藤 英治; 吉川 貴史; 他13名*
Advanced Materials, 37(8), p.2411459_1 - 2411459_11, 2025/02
被引用回数：1 パーセンタイル：0.00(Chemistry, Multidisciplinary)Twistronics, a novel engineering approach involving the alignment of van der Waals (vdW) integrated two-dimensional materials at specific angles, has recently attracted significant attention. Novel nontrivial phenomena have been demonstrated in twisted vdW junctions (the so-called magic angle), such as unconventional superconductivity, topological phases, and magnetism. However, there have been only few reports on integrated vdW layers with large twist angles 
, such as twisted interfacial Josephson junctions using high-temperature superconductors. Herein, vdW homojunctions of the thin-magnetic flakes, Fe
GeTe
(FGT), with large ranging from 0 to 90 deg, without inserting any tunnel barriers are assembled. Nevertheless, these vdW homojunctions exhibit tunnel-magnetoresistance (TMR) like behavior (pseudo-TMR (PTMR) effect) with the ratios highly sensitive to the values, revealing that the vdW gap at the junction interface between the twisted FGT layers behaves like a tunnel barrier and the serves a control parameter for PTMR by drastically varying magnitudes of the lattice-mismatch and the subsequent appearance of antiferromagnetic (AFM) spin alignment. First-principles calculations considering vacuum gaps indicate strong dependence of TMR on the driven by the sixfold screw rotational symmetry of bulk FGT. The present homojunctions hold promise as a platform for novel AFM spin-dependent phenomena and spintronic applications.
能崎 幸雄*; 介川 裕章*; 渡邉 紳一*; 柚木 清司*; 洞口 泰輔*; 中山 颯人*; 山野井 一人*; Wen, Z.*; He, C.*; Song, J.*; et al.
Science and Technology of Advanced Materials, 26(1), p.2428153_1 - 2428153_39, 2025/02
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We present a novel method for generating spin currents using the gyromagnetic effect, a phenomenon discovered over a century ago. This effect, crucial for understanding the origins of magnetism, enables the coupling between various macroscopic rotational motions and electron spins. While higher rotational speeds intensify the effect, conventional mechanical rotations, typically, below 10,000 RPM, produce negligible results comparable to geomagnetic fluctuations, limiting applied research. Our studies demonstrate that spin current generation comparable to that of rare metals can be achieved through atomic rotations induced by GHz- range surface acoustic waves and the rotational motion of conduction electrons in metallic thin films with nanoscale gradient modulation of electrical conductivity. These effects, termed the acoustic gyromagnetic effect and the current-vorticity gyromagnetic effect, are significant in different contexts.
neutron imaging and diffraction analysis revealing spatial lithiation phase evolution in an ultra-thick graphite electrodeStrobl, M.*; Baur, M. E.*; Samothrakitis, S.*; Molamud, F.*; Zhang, X.*; Tung, P. K. M.*; Schmidt, S.*; Woracek, R.*; Lee, J.*; 鬼柳 亮嗣; et al.
Advanced Energy Materials, p.2405238_1 - 2405238_9, 2025/01
Energy-efficient, safe, and reliable Li-ion batteries (LIBs) are required for a wide range of applications. The introduction of ultra-thick graphite anodes, desired for high energy densities, meets limitations in internal electrode transport properties, leading to detrimental consequences. Yet, there is a lack of experimental tools capable of providing a complete view of local processes. Here, a multi-modal measurement approach is introduced, enabling quantitative spatio-temporal observations of Li concentrations and intercalation phases in ultra-thick graphite electrodes. Neutron imaging and diffraction concurrently provide correlated multiscale information from the scale of the cell down to the crystallographic scale. In particular, the evolving formation of the solid electrolyte interphase (SEI), observation of gradients in total lithium content, as well as in the formation of ordered Li
C
phases and trapped lithium are mapped throughout the first charge-discharge cycle of the cell. Different lithiation stages co-exist during charging and discharging; delayed lithiation and delithiation processes are observed in central regions of the electrode, while the SEI formation, potential plating, and dead lithium are predominantly found closer to the interface with the separator. The study emphasizes the potential to investigate Li-ion diffusion and the kinetics of lithiation phase formation in thick electrodes.
堀内 皓斗*; 荒木 康史; 若林 勇希*; 家田 淳一; 山ノ内 路彦*; 他7名*
Advanced Materials, p.2416091_1 - 2416091_9, 2025/00
被引用回数：0Spin Berry curvature characterizes the band topology as the spin counterpart of Berry curvature and is crucial in generating novel spintronics functionalities. By breaking the crystalline inversion symmetry, the spin Berry curvature is expected to be significantly enhanced; this enhancement will increase the intrinsic spin Hall effect in ferromagnetic materials and, thus, the spin-orbit torques (SOTs). However, this intriguing approach is not applied to devices; generally, the spin Hall effect in ferromagnet/heavy-metal bilayer is used for SOT magnetization switching. Here, SOT-induced partial magnetization switching is demonstrated in a single layer of a single-crystalline Weyl oxide SrRuO (SRO) with a small current density of 
. Detailed analysis of the crystal structure in the seemingly perfect periodic lattice of the SRO film reveals barely discernible oxygen octahedral rotations with angles of 
near the interface with a substrate. Tight-binding calculations indicate that a large spin Hall conductivity is induced around small gaps generated at band crossings by the synergy of inherent spin-orbit coupling and band inversion due to the rotations, causing magnetization reversal. The results indicate that a minute atomic displacement in single-crystal films can induce strong intrinsic SOTs that are useful for spin-orbitronics devices.
清原 慎*; 都留 智仁; 熊谷 悠*
Science and Technology of Advanced Materials, 25(1), p.2393567_1 - 2393567_9, 2024/09
被引用回数：1 パーセンタイル：35.94(Materials Science, Multidisciplinary)セラミック材料においても塑性変形が生じることは知られているが、金属と比べてほとんど研究されていない。例えば、MgOは典型的なセラミックスの1つであり、実験的にも理論的にも広く研究されている。しかし、転位についての理解は進んでおらず、刃状転位とらせん転位のどちらが滑りやすいかについてさえ、未だ議論されている。本研究では、第一原理計算に基づいてMgOの転位芯の原子構造を直接モデル化し、パイエルス応力を推定した。その結果、主すべり系のらせん転位は刃状転位よりもパイエルス応力が小さいことが明らかになった。この傾向は金属と完全に異なっており、TiNで知られる傾向と一致しており、セラミックス固有の特性であることが示唆される。
substrate小幡 玲二*; 齊藤 英治; 吉川 貴史; 他7名*
Advanced Materials, 36(19), p.2311339_1 - 2311339_8, 2024/05
被引用回数：0 パーセンタイル：0.00(Chemistry, Multidisciplinary)SrTiO (STO) substrate, a perovskite oxide material known for its high dielectric constant (epsilon), facilitates the observation of various (high-temperature) quantum phenomena. A quantum Hall topological insulating (QHTI) state, comprising two copies of QH states with antiparallel two ferromagnetic edge-spin overlap protected by the U(1) axial rotation symmetry of spin polarization, has recently been achieved in low magnetic field (B) even as high as approximate to 100 K in a monolayer graphene/thin hexagonal boron nitride (hBN) spacer placed on an STO substrate, thanks to the high epsilon of STO. Despite the use of the heavy STO substrate, however, proximity-induced quantum spin Hall (QSH) states in 2D TI phases, featuring a topologically protected helical edge spin phase within time-reversal-symmetry, is not confirmed. Here, with the use of a monolayer hBN spacer, it is revealed the coexistence of QSH (at B = 0T) and QHTI (at B not equal 0) states in the same single graphene sample placed on an STO, with a crossover regime between the two at low B. It is also classified that the different symmetries of the two nontrivial helical edge spin phases in the two states lead to different interaction with electron-puddle quantum dots, caused by a local surface pocket of the STO, in the crossover regime, resulting in a spin dephasing only for the QHTI state. The results obtained using STO substrates open the doors to investigations of novel QH spin states with different symmetries and their correlations with quantum phenomena. This exploration holds value for potential applications in spintronic devices.
Liss, K.-D.*; 徐 平光; 城 鮎美*; Zhang, S. Y.*; 行武 栄太郎*; 菖蒲 敬久; 秋田 貢一*
Advanced Engineering Materials, 26(4), p.202300470_1 - 202300470_9, 2024/02
被引用回数：5 パーセンタイル：42.21(Materials Science, Multidisciplinary)In polycrystals, grains with certain orientations grow at high temperatures at the expense of grains with other unfavorable orientations. Grain growth involves a variety of situations and mechanisms that make experimental study, modeling, and understanding extremely complex. Normal grain growth occurs in a self-similar manner, with curved grain boundaries serving as the driving force and a parabolic growth law that scales up the grain size by the square root of time. More complex growth forms include boundary pinning of precipitates and other boundaries, topological transitions that alter driving forces, grain coalescence and anomalous grain growth, but these are considered "erratic" and their initiation is an open question in modern research, without a simple experimental approach on how they should be studied. Here, we show that grain rotation upon coalescence is spontaneously activated between one grain and a favorable neighbor, through the necessary diffusive mass transport at further boundaries of the same grain leading to their activation and a competitive "erratic" reorientation in a zigzag way, while other grains in the matrix remain stable. After two grains have eventually coalesced, their surrounding boundaries are still activated leading to further rotation and growth, filling the missing puzzle stone in thermodynamic theory between normal and abnormal growth, the latter stating that abnormal growth only takes place when the size of the growing grain is already large. Prerequisites and postulates of abnormal grain growth are based on advantageous texture, grain boundary mobility, enhanced diffusion kinetics and coalescence, which can be well explained by our observations. Moreover, our observations have been enabled through a novel experimental approach using the white-beam X-ray Laue diffraction method in bulk transmission mode on a polycrystalline.
Meer, H.*; Wust, S.*; Schmitt, C.*; Herrgen, P.*; Fuhrmann, F.*; Hirtle, S.*; Bednarz, B.*; Rajan, A.*; Ramos, R.*; Ni
o, M. A.*; et al.
Advanced Functional Materials, 33(21), p.2213536_1 - 2213536_6, 2023/05
被引用回数：6 パーセンタイル：58.52(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 N
el 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.
Maamoun, I.; Falyouna, O.*; Shariful, I. M.*; Eljamal, R.*; Bensaida, K.*; 田中 万也; 徳永 紘平; Eljamal, O.*
Advanced Materials Letters (Internet), 14(2), p.23021721_1 - 23021721_10, 2023/04
Arsenic (As) contamination of water has been considered as an issue of great concern. In this study, we developed magnesium hydroxide coated iron nanoparticles (nFe0@Mg(OH)) for enhancing arsenic removal from aqueous solutions. For a practical use, several parameters were investigated, including Mg/Fe coating ratio, nFe0@Mg(OH) dosage, initial pH, reaction temperature, and initial As(V) concentration.
Xu, X.*; 大平 拓実*; Xu, S.*; 平田 研二*; 大森 俊洋*; 植木 洸輔*; 上田 恭介*; 成島 尚之*; 長迫 実*; 貝沼 亮介*; et al.
Advanced Materials & Processes, 180(7), p.35 - 37, 2022/10
Metallic biomaterials are widely used to replace or support failing hard tissues due to excellent mechanical properties and high wear resistance, with demand increasing as the global population continues to age. It is widely accepted that successful metallic biomaterials should have good biocompatibility, high corrosion resistance, and strong wear resistance. In addition, a low Young's modulus similar to human bone is now recognized as another important factor, in order to avoid bone atrophy due to the stress shielding effect. While the Young's modulus of stainless steels and conventional fcc CoCr alloys is as high as 190-240 GPa, for 
-type Ti-base alloys it is generally in the range of 50-80 GPa. Young's modulus values are as low as 35 GPa for Ti-Nb-Ta-Zr, close to that of human bone at approximately 10-30 GPa. However, Ti-base alloys come with the compromise of low wear resistance. In fact, alloys that feature a low Young's modulus along with high wear resistance have been difficult to realize. This article explores the recently developed bcc CoCr-base alloy Co-Cr-Al-Si as a potential solution to these issues, i.e., the difficulty in combining a low Young's modulus with high wear resistance, and the challenge of realizing large superelastic strains.
大平 拓実*; Xu, S.*; 平田 研二*; Xu, X.*; 大森 俊洋*; 植木 洸輔*; 上田 恭介*; 成島 尚之*; 長迫 実*; Harjo, S.; et al.
Advanced Materials, 34(27), p.2202305_1 - 2202305_11, 2022/07
被引用回数：30 パーセンタイル：89.52(Chemistry, Multidisciplinary)The demand for biomaterials has been increasing along with the increase in the population of elderly people worldwide. The mechanical properties and high wear resistance of metallic biomaterials makes them well-suited for use as substitutes or as support for damaged hard tissues. However, unless these biomaterials also have a low Young's modulus similar to that of human bones, bone atrophy inevitably occurs. Because a low Young's modulus is typically associated with poor wear resistance, it is difficult to realize a low Young's modulus and high wear resistance simultaneously. Also, the superelastic property of shape memory alloys makes them suitable for biomedical applications, like vascular stents and guide wires. However, due to the low recoverable strain of conventional biocompatible shape memory alloys, the demand for a new alloy system is high. The novel body-center-cubic cobalt-chromium-based alloys in this paper provide a solution to both of these problems. We believe our novel alloys are promising candidates for biomedical applications.
temperature measurement for lamp-based heating device墨田 岳大; 須藤 彩子; 高野 公秀; 池田 篤史
Science and Technology of Advanced Materials; Methods (Internet), 2(1), p.50 - 54, 2022/02
Despite a wide variety of its practical applications, handiness, and cost-effectiveness, the advance of lamp-based heating device is obstructed by one technical difficulty in measuring the temperature on a heated material. This difficulty originates in the combination of polychromatic light source and a radiation thermometer that determines temperature from radiation (i.e. light). A new system developed in this study overcomes this intrinsic difficulty by measuring exclusively the radiation from the heated material, allowing us to perform the direct and measurement of temperature in a light-based heating device (an arc image furnace). Test measurements demonstrated the reliability of temperature measurement using the developed system as well as its promising potential for the determination of emissivity at high temperature particularly in the infrared region.
大平 征史*; 片島 拓弥*; 内藤 瑞*; 青木 大輔*; 吉川 祐介*; 岩瀬 裕希*; 高田 慎一; 宮田 完二郎*; Chung, U.-I.*; 酒井 崇匡*; et al.
Advanced Materials, 34(13), p.2108818_1 - 2108818_9, 2022/01
被引用回数：23 パーセンタイル：88.23(Chemistry, Multidisciplinary)DNA duplexes are ideal crosslinkers for building such gels because of their excellent sequence addressability and flexible tunability in bond energy. However, the mechanical responses of most DNA gels are complicated and unpredictable. The melting curve analysis of the DNA gels reveals the good correspondence between the thermodynamic potentials of the DNA crosslinkers and the presimulated values by DNA calculators. Stress-relaxation tests and dissociation kinetics measurements show that the macroscopic relaxation time of the DNA gels is approximately equal to the lifetime of the DNA crosslinkers over 4 orders of magnitude from 0.1-2000 s. Furthermore, a series of durability tests find the DNA gels are hysteresis-less and self-healable after the applications of repeated temperature and mechanical stimuli.
O vapor on GaN surfaces角谷 正友*; 隅田 真人*; 津田 泰孝; 坂本 徹哉; Sang, L.*; 原田 善之*; 吉越 章隆
Science and Technology of Advanced Materials, 23(1), p.189 - 198, 2022/00
被引用回数：6 パーセンタイル：40.55(Materials Science, Multidisciplinary)GaNは、パワーエレクトロニクスデバイスとして注目される材料である。GaNの表面酸化の理解は、金属-酸化膜-半導体(MOS)デバイスを改善するために重要である。本研究では、GaNの結晶面(+c,-c,m-面)毎の酸化特性を、リアルタイムXPSとDFT-MDシミュレーションによって調べた。その結果、HOとGaN表面との間のスピン相互作用によりHO蒸気が最も高い反応性を示すことがわかった。m面では、化学吸着が支配的であった。本研究は、AlGa
N原子層成膜時に意図しない酸化を防ぐために、HOおよびO以外の酸化剤ガスを使用する必要があることを示唆している。
Co
Ni
Al
TiMo medium-entropy alloy; In situ neutron diffraction analysisKwon, H.*; Harjo, S.; 川崎 卓郎; Gong, W.; Jeong, S. G.*; Kim, E. S.*; Sathiyamoorthi, P.*; 加藤 秀実*; Kim, H. S.*
Science and Technology of Advanced Materials, 23(1), p.579 - 586, 2022/00
被引用回数：12 パーセンタイル：62.47(Materials Science, Multidisciplinary)Metastability engineering is a strategy to enhance the strength and ductility of alloys via deliberately lowering phase stability and prompting deformation-induced martensitic transformation. In this work, the martensitic transformation and its effect on the mechanical response of a FeCoNiAlTiMo medium-entropy alloy (MEA) were studied by in situ neutron diffraction under tensile loading. This work shows how great a role FCC to BCC martensitic transformation can play in enhancing the mechanical properties of ferrous MEAs.
川崎 陸*; 佐々木 善浩*; 西村 智貴*; 片桐 清文*; 森田 圭一*; 関根 由莉奈; 澤田 晋一*; 向井 貞篤*; 秋吉 一成*
Advanced Healthcare Materials, 10(9), p.2001988_1 - 2001988_8, 2021/05
被引用回数：12 パーセンタイル：58.70(Engineering, Biomedical)機能性タンパク質の細胞内送達である「タンパク質形質導入」のためのシステムは、タンパク質治療の送達可能性の課題に対処するために必要であるが、in vivoでのタンパク質導入は依然として困難である。本研究では、酸化鉄ナノ粒子と多糖類ナノゲルで構成される磁性ナノゲルシャペロン(MC)を使用した磁気誘導in vivoタンパク質形質導入システムを開発した。口腔癌モデルを用いた実験により、本MCシステムが癌治療に有用であることが示された。
Kong, L.*; Gong, J.*; Hu, Q.*; Capitani, F.*; Celeste, A.*; 服部 高典; 佐野 亜沙美; Li, N.*; Yang, W.*; Liu, G.*; et al.
Advanced Functional Materials, 31(9), p.2009131_1 - 2009131_12, 2021/02
被引用回数：32 パーセンタイル：82.55(Chemistry, Multidisciplinary)有機-無機ハロゲン化物ペロブスカイトは非常に柔らかいために、圧力などの外部刺激により格子定数を容易に変化させることができ、有用な光電特性を引き出すのに有効である。一方でこの特性は、多少の加圧でも、格子を歪ませてしまい、光と物質の相互作用を弱め、それによる性能の低下を引き起こす。そこで本研究では、代表的な物質であるヨウ化メチルアンモニウム鉛に対して圧力効果および同位体効果を調べ、それらが格子歪を抑制することが分かった。このことは、それらが、これまで得られなかったような光学的,機械的特性を持つ物質を得る手段として有効であることを示している。
直江 崇; 勅使河原 誠; 二川 正敏; 水谷 春樹; 村松 壽晴; 山田 知典; 牛塚 悠司*; 田中 伸厚*; 山崎 和彦*
Proceedings of 8th International Congress on Laser Advanced Materials Processing (LAMP 2019) (Internet), 5 Pages, 2019/05
レーザー切断は、J-PARC核破砕中性子源標的容器等の放射性廃棄物の減容処分方法の1つである。レーザーによる切断は、非接触で実施されるため従来の機械切断方法等と比較して遠隔操作による切断作業に適している。しかしながらレーザーは、切断時に生じる放射性物質を含むスパッタやヒュームの飛散が、周囲に汚染を広げるデメリットがある。近年、レーザー溶接において、ビームプロファイルの制御によるスパッタ飛散の低減技術が開発された。レーザー切断に本技術を適用する手始めとして、レーザー切断時における溶融部の挙動について物理モデルを構築するために、高速度ビデオカメラを用いて溶融部を可視化した。その結果、ヒュームとスパッタの発生は、時間的に独立していることを確認した。
末國 晃一郎*; Lee, C. H.*; 田中 博己*; 西堀 英治*; 中村 篤*; 笠井 秀隆*; 森 仁志*; 臼井 秀知*; 越智 正之*; 長谷川 巧*; et al.
Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03
被引用回数：62 パーセンタイル：89.45(Chemistry, Multidisciplinary)高性能デバイスとしての熱電材料には、高い電気伝導度と低い熱伝導度という相反する要求を同時に満たす必要がある。本研究では、テトラへドライト(Cu,Zn)
(Sb,As)
S
の結晶構造とフォノンダイナミクスを調べ、平面内に配位している銅原子のラットリング運動がフォノンを効率良く散乱することを見出した。これらの知見は、平面配位構造を有する高性能熱電材料の新たな開発指針を与えるものである。
Tremsin, A. S.*; Gao, Y.*; Dial, L. C.*; Grazzi, F.*; 篠原 武尚
Science and Technology of Advanced Materials, 17(1), p.324 - 336, 2016/07
被引用回数：21 パーセンタイル：54.03(Materials Science, Multidisciplinary)Non-destructive testing techniques based on neutron imaging and diffraction can provide information on the internal structure of relatively thick metal samples (up to several cm), which are opaque to other conventional non-destructive methods. Spatially resolved neutron transmission spectroscopy is an extension of traditional neutron radiography, where multiple images are acquired simultaneously, each corresponding to a narrow range of energy. The analysis of transmission spectra enables studies of bulk microstructures at the spatial resolution comparable to the detector pixel. In this study we demonstrate the possibility of imaging (with about 100 
m resolution) distribution of some microstructure properties, such as residual strain, texture, voids and impurities in Inconel 625 samples manufactured with an additive manufacturing method called direct metal laser melting (DMLM).
