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論文

$^{149}$ Sm synchrotron-radiation-based Mssbauer and SR studies of SmRuGe $_{13}$

筒井智嗣; 伊藤孝; 中村仁*; 吉田実生*; 小林義男*; 依田芳卓*; 中村惇平*; 幸田章宏*; 東中隆二*; 青木大*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

https://doi.org/10.1007/s10751-024-01900-6

$^{149}$ Sm SR-based Mssbauer and muon spin relaxation (SR) spectroscopies have been applied to SmRuGe $_{13}$ . The temperature dependence of the $^{149}$ Sm SR-based Mssbauer spectra in the paramagnetic state implies the presence of dynamical nuclear Zeeman and/or quadrupole interactions. The time differential SR spectra also exhibit a marked temperature dependence in the paramagnetic state, indicating the presence of magnetic fluctuation in SmRuGe $_{13}$ at least. These results in the present work infer that the dynamical hyperfine interactions observed using the mutually complementary spectroscopic methods are connected with the mechanism of the heavy fermion behavior in SmRuGe $_{13}$ .

論文

Pulsed muon facility of J-PARC MUSE

下村浩一郎*; 幸田章宏*; Pant, A. D.*; 砂川光*; 藤森寛*; 梅垣いづみ*; 中村惇平*; 藤原理賀; 反保元伸*; 河村成肇*; et al.

Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12

https://doi.org/10.1007/s10751-024-01863-8

J-PARC Muon Facility: MUSE (Muon Science Establishment) is responsible for the inter-university user program and the operation, maintenance, and construction of the muon beamlines, namely D-line, S-line, U-line, and H-line, along with the muon source at J-PARC Materials and Life Science Facility (MLF). In this paper, recent developments are briefly presented.

論文

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy of Sm-based heavy fermion compounds

筒井智嗣; 東中隆二*; 水牧仁一朗*; 小林義男*; 中村仁*; 伊藤孝; 依田芳卓*; 松田達磨*; 青木勇二*; 佐藤英行*

Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12

https://doi.org/10.1007/s10751-024-01851-y

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy has been applied to Sm-based heavy fermion intermetallics, SmAl $_{20}$ ( = Ti, V and Cr) and SmOs $_{4}$ Sb $_{12}$ . The isomer shifts obtained demonstrate that the Sm valence states in these compounds are intermediate. Since the difference of the isomer shifts in 22.502 keV $^{149}$ Sm Mssbauer effect between Sm $^{2+}$ and Sm $^{3+}$ state is comparable to the 2nd order Doppler shift, consideration of the 2nd order Doppler shift is required to precisely discuss Sm valence state through the shifts of the Mssbauer spectra. In addition, the plots of the isomer shifts obtained by the Mssbauer spectroscopy against the Sm valence states estimated from Sm L-edge X-ray absorption spectroscopy exhibit a linear correlation except for that in SmOsSb $_{12}$ . This implies that the origin of the intermediate valence state in SmOsSb $_{12}$ differs from that in SmAl $_{20}$ ( = Ti, V and Cr).

論文

Muon spin relaxation in mixed perovskite (LaAlO)(SrAl $_{0.5}$ Ta $_{0.5}$ O) $_{1-x}$ with

伊藤孝; 髭本亘; 幸田章宏*; 中村惇平*; 下村浩一郎*

Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12

https://doi.org/10.1007/s10751-024-01866-5

We report on muon spin relaxation (SR) measurements in a mixed perovskite compound, (LaAlO) $_{x}$ (SrAl $_{0.5}$ Ta $_{0.5}$ O) $_{1-x}$ with (LSAT), which is widely used as a single-crystalline substrate for thin film deposition. In zero applied field (ZF), muon depolarization due to the distribution of nuclear dipole fields was observed in the temperature range from 4 K to 270 K. Interestingly, SR time spectra in ZF maintained a Gaussian-like feature over the entire range, while the depolarization rate exhibited a monotonic decrease with increasing temperature. This behavior may be attributed to the thermally activated diffusion of muons between a few adjacent sites within a confined space of the angstrom scale, where the motionally averaged local field that each muon experiences can remain non-zero and result in maintaining the Gaussian-like line shape. The spatial distribution of electrostatic potential at lattice interstices evaluated via density functional theory calculations suggests that such a restriction of muon diffusion paths can be caused by the random distribution of cations with different nominal valences in the mixed perovskite lattice.

論文

Oxide particles in oxide dispersion strengthened steel neutron-irradiated up to 158 dpa at Joyo

外山健*; 丹野敬嗣; 矢野康英; 井上耕治*; 永井康介*; 大塚智史; 宮澤健; 光原昌寿*; 中島英治*; 大沼正人*; et al.

Journal of Nuclear Materials, 599, p.155252_1 - 155252_14, 2024/10

https://doi.org/10.1016/j.jnucmat.2024.155252

高速実験炉「常陽」で中性子照射した14Cr-ODS鋼(MA957)中の酸化物の安定性について3D-APとTEMを用いて評価を行った。中性子照射は、(502 $^{circ}$ C, 130dpa)、(589 $^{circ}$ C, 154dpa)及び(709 $^{circ}$ C, 158dpa)の3条件で実施した。709 $^{circ}$ C照射では僅かな数密度の減少が認められたが、酸化物は高い数密度を有しており、相対的に照射前後で顕著な変化は確認されず安定に存在していた。これらのことから、ODS鋼は、700 $^{circ}$ C照射で約160dpaまで照射されたとしても強度は維持されることが示唆された。本研究成果の一部は、文部科学省の原子力システム研究開発事業による委託業務(JPMXD0219214482)として実施した。

論文

Development of a non-destructive carbon quantification method in iron by negative muon lifetime measurement

二宮和彦*; 久保謙哉*; 稲垣誠*; 吉田剛*; 竹下聡史*; 反保元伸*; 下村浩一郎*; 河村成肇*; Strasser, P.*; 三宅康博*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 333(7), p.3445 - 3450, 2024/07

https://doi.org/10.1007/s10967-023-09289-2

A novel nondestructive light element analysis method for bulk materials using muon beams was demonstrated. This method is based on the lifetime measurement of muons in a material and performed by measuring muon-decay electrons and identifying elements using the atomic number based on muon lifetimes. Muon irradiation on pure iron and two steel samples with known carbon contents was conducted to prepare a calibration curve for the quantitative analysis. We also performed a muon lifetime measurement for a Japanese sword and successfully determined its carbon content as 0.51 wt% using the calibration curve, without sample destruction.

報告書

HTTR1次ヘリウム循環機フィルタの差圧上昇事象,2; フィルタ付着物の調査と再発防止対策

根本隆弘; 藤原佑輔; 荒川了紀; 長山侑矢; 長住達; 長谷川俊成; 横山佳祐; 渡部雅; 大西貴士; 川本大樹; et al.

JAEA-Technology 2024-003, 17 Pages, 2024/06

JAEA-Technology-2024-003.pdf:1.91MB

RS-14サイクルに発生した1次ヘリウム循環機フィルタの差圧上昇の原因を調査するため、フィルタ付着物を調査した。調査の結果、フィルタエレメント表面にシリコンオイルに起因する付着物を確認した。この結果から、フィルタ差圧上昇の原因は、1次ヘリウム純化設備ガス循環機のチャコールフィルタの性能劣化により、1次系内にシリコンオイルが混入したためであることが明らかとなった。また、この再発防止対策として、従来の1次ヘリウム純化設備ガス循環機の運転時間による管理に加え、チャコールフィルタの交換頻度を3年毎とする定期交換計画を新たに策定した。

論文

Creep deformation and rupture behavior of 9Cr-ODS steel cladding tube at high temperatures from 700 $^{circ}$ C to 1000 $^{circ}$ C

今川裕也; 橋立竜太; 宮澤健; 鬼澤高志; 大塚智史; 矢野康英; 丹野敬嗣; 皆藤威二; 大沼正人*; 光原昌寿*; et al.

Journal of Nuclear Science and Technology, 61(6), p.762 - 777, 2024/06

https://doi.org/10.1080/00223131.2023.2269178

日本原子力研究開発機構は、ナトリウム冷却高速炉(SFR)の燃料被覆管材料として9Cr-ODS鋼の開発を進めている。これまでの研究で、650 $^{circ}$ Cから850 $^{circ}$ Cを対象にクリープ破断式が策定されている。本研究では、700 $^{circ}$ Cから1000 $^{circ}$ Cでのクリープ強度評価を目的とし、クリープ試験を実施した。クリープ試験には内圧クリープ試験法と開発中のリングクリープ試験法の2種類の試験方法を使用し、リングクリープ試験方法の妥当性の検証も合わせて実施した。その結果、9Cr-ODS鋼は母相の相変態による強度変化がほとんど起こらず、700 $^{circ}$ Cから1000 $^{circ}$ Cまでを対象に一つの式でクリープ破断傾向を表せることが明らかとなった。リングクリープ試験方法の妥当性検証では、解析により試験片への応力集中の影響を明らかにした。初期応力が高いと塑性変形が起こり、早期破断に至る可能性がある。これらの検討の結果は、今後、中性子照射した9Cr-ODS鋼のクリープ試験の実施と評価をする際に不可欠である。

論文

Formulation of high-temperature strength equation of 9Cr-ODS tempered martensitic steels using the Larson-Miller parameter and life-fraction rule for rupture life assessment in steady-state, transient, and accident conditions of fast reactor fuel

宮澤健; 丹野敬嗣; 今川裕也; 橋立竜太; 矢野康英; 皆藤威二; 大塚智史; 光原昌寿*; 外山健*; 大沼正人*; et al.

Journal of Nuclear Materials, 593, p.155008_1 - 155008_16, 2024/05

https://doi.org/10.1016/j.jnucmat.2024.155008

This paper discusses the applicability of J.L. Straalsund et al.'s technique for combining the Larson-Miller parameter (LMP) and life-fraction rule to form a single high-temperature strength equation for 9Cr- oxide-dispersion-strengthened (ODS) tempered martensitic steels (TMS). It uses the extensive dataset on creep rupture, tensile, and temperature-transient-to-burst tests of 9Cr-ODS TMS cladding tubes in the -phase, /-duplex, -phase matrices, which are accumulated by the Japan Atomic Energy Agency so far. The technique is adequately applicable to 9Cr-ODS TMS cladding tubes. A single high-temperature strength equation expressing the mechanical strength in different deformation and rupture modes (creep, tensile, temperature-transient-to-burst) is derived for 9Cr-ODS TMS cladding tubes. This equation can predict the rupture life of the cladding tubes under various stresses and temperatures over time. The applicable range of the high-temperature strength equation is specified in this study and the upper limit temperature for the equation is found to be 1200 $^{circ}$ C. At temperatures higher than 1200 $^{circ}$ C, the coarsening and aggregation of nanosized oxide particles and the to phase transformation are reported in previous studies. The high-temperature strength equation can be well applied to the creep and tensile strength in the -phase matrix, the creep strength in the -phase matrix and the temperature-transient-to-burst strength in both phases except for the low equivalent stress (43 MPa) at temperatures exceeding 1050 $^{circ}$ C. The mechanism of the notable consistency between creep and tensile strength in the -phase matrix is discussed by analyzing the high-temperature deformation data in the light of existing deformation models.

論文

Tensile properties of modified 316 stainless steel (PNC316) after neutron irradiation over 100 dpa

矢野康英; 上羽智之; 丹野敬嗣; 吉武庸光; 大塚智史; 皆藤威二

Journal of Nuclear Science and Technology, 61(4), p.521 - 529, 2024/04

https://doi.org/10.1080/00223131.2023.2243943

被引用回数：1 パーセンタイル：63.33(Nuclear Science & Technology)

高速実験炉「常陽」で中性子照射したPNC316の引張特性に及ぼす中性子の影響を評価した。PNC316被覆管とラッパ管は、照射温度400ら735 $^{circ}$ Cで照射量21から125dpaで照射された。照射後の引張試験は室温と照射温度で実施された。照射材の著しい硬化と軟化は確認されたが、照射後の引張延性は工学的なレベルを維持できていた。また、400から500 $^{circ}$ Cの範囲で110dpa照射されたPNC316ラッパ管の最大スエリング量は2.5%であり、10%以上のスエリングが生じたPNC316や15Cr-20Ni鋼のような日本の20%冷間加工材は、塑性不安定は小さかったけれども、十分な延性と加工硬化性能を維持していることが分かった。

論文

Distinguishing ion dynamics from muon diffusion in muon spin relaxation

伊藤孝; 門野良典*

Journal of the Physical Society of Japan, 93(4), p.044602_1 - 044602_7, 2024/04

https://doi.org/10.7566/JPSJ.93.044602

被引用回数：0 パーセンタイル：0.01

We propose a model to describe the fluctuations in the internal magnetic field due to ion dynamics observed in muon spin relaxation (SR) by an Edwards-Anderson-type autocorrelation function that separates the quasi-static and dynamic components of the correlation by the parameter (where ). Our Monte Carlo simulations for this model showed that the time evolution of muon spin polarization deviates significantly from the Kubo-Toyabe function. To further validate the model, the results of simulations were compared with the SR spectra observed in a hybrid organic-inorganic perovskite FAPbI [with FA referring to HC(NH)], where local field fluctuations associated with the rotational motion of FA molecules and quasi-static fields from the PbI lattice are presumed to coexist. The least-squares curve fitting showed reasonable agreement with the model with , and the fluctuation frequency of the dynamical component was obtained. This result opens the door to the possibility of experimentally distinguishing fluctuations due to the dynamics of ions around muons from those due to the self-diffusion of muons. On the other hand, it suggests the need to carefully consider the spin relaxation function when applying SR to the issue of ion dynamics.

論文

Local structural changes in V-Ti-Cr alloy hydrides with hydrogen absorption/desorption cycling

池田一貴*; 佐次田頌*; 大友季哉*; 大下英敏*; 本田孝志*; 羽合孝文*; 齋藤開*; 伊藤晋一*; 横尾哲也*; 榊浩司*; et al.

International Journal of Hydrogen Energy, 51(Part A), p.79 - 87, 2024/01

https://doi.org/10.1016/j.ijhydene.2023.10.318

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

Low-vanadium-concentration alloys have low durability, and their hydrogen absorption and desorption amounts decrease by 20% after 100 cycles. In this study, we conducted reverse Monte Carlo modeling on X-ray diffraction patterns and neutron pair distribution functions of the hydrogen-absorbed and desorbed samples of a V $_{0.10}$ Ti $_{0.36}$ Cr $_{0.54}$ alloy to analyze the variations in the local structure. The local structure surrounding the hydrogen atom in the hydrogen-absorbed phase exhibited minimal changes. In contrast, hydrogen occupied both tetrahedral and octahedral sites of the hydrogen-desorbed phase almost equally during the early cycles; however, the amount of hydrogen occupying the tetrahedral sites increased with the number of cycles.

論文

Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis

二宮和彦*; 久保謙哉*; 稲垣誠*; 吉田剛*; Chiu, I.-H.; 工藤拓人*; 浅利駿介*; 千徳佐和子*; 竹下聡史*; 下村浩一郎*; et al.

Scientific Reports (Internet), 14, p.1797_1 - 1797_8, 2024/01

https://doi.org/10.1038/s41598-024-52255-5

被引用回数：0 パーセンタイル：0.05(Multidisciplinary Sciences)

鋼の特性を決める上で重要な鋼中のC量は、鋼の生産技術に大きく左右される。このため、ミュオンを使って鋼のC含有量を非破壊で測定する新しい方法を提案する。この方法は、生産中の鋼の品質管理だけでなく、貴重な鋼製考古学的遺物の分析にも使えるかもしれない。負の電荷を持つミュオンは原子系を形成し、最終的には核に吸収されるか電子に崩壊する。ミュオンの寿命は、Fe原子かC原子に捕らわれるかによってかなり違い、ミュオン停止位置での元素含有量をミュオン寿命測定で特定できる。C/Feのミュオン捕獲確率とCの元素含有量の関係は直線的で、ミュオン寿命測定で鋼のC含有量を定量的に決められる。さらに、ミュオンの入射エネルギーを調整して、0.5mm厚の3種類の鋼板からなる積層サンプルの各層でミュオンを停止させ、0.20-1.03wt%の範囲でC含有量を深さ選択的に、サンプルを壊さずに決定することに成功した。

論文

Ga K-edge XANES study of Ga-exchanged zeolites at high temperatures under different atmospheres including vacuum, CO, and pressurized H $_{2}$

Huang, M.*; 金城哲弥*; 安村駿作*; 鳥屋尾隆*; 松村大樹; 齋藤寛之*; 清水研一*; 並木則和*; 前野禅*

Catalysis Science & Technology, 13(23), p.6832 - 6838, 2023/12

https://doi.org/10.1039/D3CY01250F

被引用回数：0 パーセンタイル：0.00(Chemistry, Physical)

Ga-exchanged zeolites are promising catalysts for dehydrogenative alkane transformations. Reduced Ga species, such as Ga hydrides and Ga $^{+}$ cations, are possible active sites for alkane dehydrogenation based on in situ spectroscopic studies. However, most of the reported studies were conducted at lower temperatures compared with those encountered in actual operating conditions. In this study, the in situ Ga K-edge XANES analysis of Ga-exchanged MFI zeolite was performed under actual operating temperatures and different atmospheres (H $_{2}$ , He, CO, vacuum, and C $_{2}$ H $_{6}$ ). The absorption edge appeared at similarly lower energy values than that of Ga $_{2}$ O $_{3}$ in all atmospheres, whereas the main absorption peak intensity differed depending on the presence or absence of a hydride source in the gas phase. Higher intensities were observed under H $_{2}$ and C $_{2}$ H $_{6}$ atmospheres than under CO and vacuum atmospheres.

論文

Understanding muon diffusion in perovskite oxides below room temperature based on harmonic transition state theory

伊藤孝; 髭本亘; 下村浩一郎*

Physical Review B, 108(22), p.224301_1 - 224301_11, 2023/12

https://doi.org/10.1103/PhysRevB.108.224301

被引用回数：1 パーセンタイル：44.21(Materials Science, Multidisciplinary)

In positive muon spin rotation and relaxation (SR) spectroscopy, positive muons () implanted into solid oxides are conventionally treated as immobile spin-probes at interstitial sites below room temperature. This is because each is thought to be tightly bound to an oxygen atom in the host lattice to form a muonic analogue of the hydroxy group. On the basis of this concept, anomalies in SR spectra observed in oxides have been attributed in most cases to the intrinsic properties of host materials. On the other hand, global diffusion with an activation energy of 0.1~eV has been reported in some chemically-substituted perovskite oxides at cryogenic temperatures, although the reason for the small activation energy despite the formation of the strong O bond has not yet been quantitatively understood. In this study, we investigated interstitial diffusion in the perovskite oxide lattice using KTaO cubic perovskite as a model system. We used the SR method and density functional theory calculations along with the harmonic transition state theory to study this phenomenon both experimentally and theoretically. Experimental activation energies for global diffusion obtained below room temperature were less than a quarter of the calculated classical potential barrier height for a bottleneck transfer path. The reduction in the effective barrier height could be explained by the harmonic transition state theory with a zero-point energy correction; a significant difference in zero-point energies for at the positions in the O bonding equilibrium state and a bond-breaking transition state was the primary cause of the reduction. This suggests that the assumption of immobile in solid oxides is not always satisfied since such a significant decrease in diffusion barrier height can also occur in other oxides.

論文

Pd nanoparticles on the outer surface of microporous aluminosilicates for the direct alkylation of benzenes using alkanes

美崎慧*; 三輪寛子*; 伊藤孝; 吉田健文*; 長谷川慎吾*; 中村由紀奈*; 徳竹駿太*; 高畠萌*; 下村浩一郎*; Chun, W.-J.*; et al.

ACS Catalysis, 13(18), p.12281 - 12287, 2023/09

https://doi.org/10.1021/acscatal.3c02309

被引用回数：2 パーセンタイル：55.84(Chemistry, Physical)

The direct alkylation of benzenes with simple alkanes is one of the ideal processes for the production of alkylbenzenes. We demonstrated that Pd nanoparticles on the outer surface of H-ZSM-5 are efficient catalysts for direct alkylation. The reaction proceeds through the activation of an alkane on the acid sites present inside the zeolite pores. This process is followed by the nucleophilic addition of an arene to the activated alkane. The spillover of the abstracted hydrogen atoms from the acid sites to the Pd nanoparticles on the outer surface accelerates recombination to H. A maximum toluene conversion of 58.5% and selectivity of 95.6% for the alkylated products are achieved when toluene is reacted with -heptane. -selective alkylation is achieved, due to the effect of the pore size of H-ZSM-5. The SR study of muonium, a pseudo-isotope of hydrogen, in aluminosilicates suggested that the formation of atomic hydrogen is possible and its lifetime is in the sub-microsecond range or longer, which is long enough for chemical reactions.

論文

First observation of $^{28}$ O

近藤洋介*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; 馬場秀忠*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

https://doi.org/10.1038/s41586-023-06352-6

被引用回数：6 パーセンタイル：93.49(Multidisciplinary Sciences)

非常に中性子が過剰な原子核 $^{28}$ Oは、陽子、中性子ともに魔法数であることから古くからその性質に興味が持たれていたが、酸素の最後の束縛核 $^{24}$ Oよりも中性子が4個も多いため、これまで観測されてこなかった。この論文では、理化学研究所RIBFにて $^{29}$ Fからの1陽子ノックアウト反応によって $^{28}$ Oを生成し、そこから放出される中性子を測定することによって初めてその観測に成功した。核構造の観点からは、 $^{28}$ Oでは二重閉殻が保たれているか興味が持たれていたが、実験で得られた分光学的因子が殻模型計算で予言されて程度の大きいことから、閉殻構造をもたない可能性が高いことがわかった。

論文

Intruder configurations in $^{29}$ Ne at the transition into the island of inversion; Detailed structure study of $^{28}$ Ne

Wang, H.*; 安田昌弘*; 近藤洋介*; 中村隆司*; Tostevin, J. A.*; 緒方一介*; 大塚孝治*; Poves, A.*; 清水則孝*; 吉田数貴; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

https://doi.org/10.1016/j.physletb.2023.138038

被引用回数：2 パーセンタイル：79.22(Astronomy & Astrophysics)

$^{29}$ Neからの1中性子除去反応を用いて、 $^{28}$ Neの詳細な線分光を行った。平行運動量分布の解析に基づき、 $^{28}$ Neの準位構造とスピンパリティを決定し、初めて負のパリティ状態を同定した。測定された断面積と運動量分布から、N=20とN=28のシェルギャップの消失の証拠となる有意なintruder p-wave強度が明らかになった。束縛状態については、弱いf-waveの可能性のある強度が観測された。いくつかの有効相互作用を用いた大規模殻模型計算では、実験的に観測された大きなp-wave強度と小さなf-wave強度は再現されず、Ne同位体に沿った反転の島への遷移の完全な理論的記述への挑戦が続いていることを示している。

論文

Local electronic structure of interstitial hydrogen in MgH inferred from muon study

門野良典*; 平石雅俊*; 岡部博孝*; 幸田章宏*; 伊藤孝

Journal of Physics; Condensed Matter, 35(28), p.285503_1 - 285503_13, 2023/07

https://doi.org/10.1088/1361-648X/acccc7

被引用回数：0 パーセンタイル：0.00(Physics, Condensed Matter)

Magnesium hydride has great potential as a solid hydrogen (H) storage material because of its high H storage capacity of 7.6 wt%. However, its slow hydrogenation and dehydrogenation kinetics and the high temperature of 300 C required for decomposition are major obstacles to small-scale applications such as automobiles. The local electronic structure of interstitial H in MgH is an important fundamental knowledge in solving this problem, which has been studied mainly based on density functional theory (DFT). However, few experimental studies have been performed to assess the results of DFT calculations. We have therefore introduced muon (Mu) as pseudo-H into MgH and investigated the corresponding interstitial H states by analyzing their electronic and dynamical properties in detail. As a result, we observed multiple Mu states similar to those observed in wide-gap oxides, and found that their electronic states can be attributed to relaxed-excited states associated with donor/acceptor levels predicted by the recently proposed ambipolarity model. This provides an indirect support for the DFT calculations on which the model is based via the donor/acceptor levels. An important implication of the muon results for improved hydrogen kinetics is that dehydrogenation, serving as a reduction for hydrides, stabilises the interstitial H state.

論文

Single crystal growths and magnetic properties of hexagonal polar semimetals AuGe ( = Y, Gd-Tm, and Lu)

車地崇*; 厳正輝*; 鬼頭俊介*; 池内和彦*; 中村充孝; 池田暁彦*; 有馬孝尚*

Journal of Alloys and Compounds, 947, p.169475_1 - 169475_8, 2023/06

https://doi.org/10.1016/j.jallcom.2023.169475

被引用回数：1 パーセンタイル：44.33(Chemistry, Physical)

We study structural and magnetic properties of rare-earth based semimetals AuGe ( = Y, Gd-Tm, and Lu) using flux-grown single crystals. We evaluate the crystal electric field parameters based on the Stevens operators to reasonably reproduce the temperature dependence of magnetic susceptibilities and specific heat for RAuGe ( = TbTm). The estimated energy scale of the Ising gap ( 11 meV) in TmAuGe is consistent with an excitation observed in an inelastic neutron scattering experiment. These findings suggest an opportunity for interplay between conduction electrons and nontrivial spin structures in the family of magnetic polar semimetals AuGe.