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論文

Possible field-induced quantum state in a rhombic lattice antiferromagnet KCoPO$$_{4}$$$$cdot$$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：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

We reported the magnetic behavior of a rhombic lattice quantum antiferromagnet KCoPO$$_{4}$$$$cdot$$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 $$J$$$$_{rm{eff}}$$ = 1/2 state. The magnetic structure of KCoPO$$_{4}$$$$cdot$$H$$_{2}$$O is identified as an incommensurate helical structure, characterized by a magnetic modulation propagation vector $$bold{k}$$ = (0.1747(1) 0 0) with an in-plane moment rotating along the $$a$$ 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

Recent status of the cryogenic sample environment at the MLF, J-PARC

石角 元志*; 高橋 竜太*; 山内 康弘*; 中村 雅俊*; 石丸 宙*; 山内 沙羅*; 河村 聖子; 吉良 弘*; 坂口 佳史*; 渡辺 真朗; et al.

JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05

https://doi.org/10.7566/JPSCP.41.011010

Recent status of cryogenic sample environment equipment at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC) has been reported. We have reviewed the specifications and performance of cryogenic sample environment equipment and a newly installed Gifford-McMahon (GM) cryofurnace, which are mainly managed by the Cryogenic and Magnet group in the sample environment team at the MLF. Moreover, the recent maintenance and update of each piece of equipment, the improved temperature-control function, and the expansion of the usable beamline of the cryogenic sample environment equipment are described.

論文

Spin dependence in the $$p$$-wave resonance of $$^{139}$$$overrightarrow{textrm{La}}$+$overrightarrow{n}$

奥平 琢也*; 中部 倫太郎*; Auton, C. J.*; 遠藤 駿典; 藤岡 宏之*; Gudkov, V.*; 井出 郁央*; 猪野 隆*; 石角 元志*; 神原 理*; et al.

Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04

https://doi.org/10.1103/PhysRevC.109.044606
 被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)

We measured the spin dependence in a neutron-induced p-wave resonance by using a polarized epithermal neutron beam and a polarized nuclear target. Our study focuses on the 0.75 eV $$p$$-wave resonance state of $$^{139}$$La+n, where largely enhanced parity violation has been observed. We determined the partial neutron width of the $$p$$-wave resonance by measuring the spin dependence of the neutron absorption cross section between polarized $$^{139}$$La and polarized neutrons. Our findings serve as a foundation for the quantitative study of the enhancement effect of the discrete symmetry violations caused by mixing between partial amplitudes in the compound nuclei.

論文

High sensitivity of a future search for effects of $$P$$-odd/$$T$$-odd interactions on the 0.75 eV $$p$$-wave resonance in $$overrightarrow{n}$$+$$^{139}overrightarrow{textrm{La}}$$ forward transmission determined using a pulsed neutron beam

中部 倫太郎*; Auton, C. J.*; 遠藤 駿典; 藤岡 宏之*; Gudkov, V.*; 広田 克也*; 井出 郁央*; 猪野 隆*; 石角 元志*; 神原 理*; et al.

Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04

https://doi.org/10.1103/PhysRevC.109.L041602
 被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)

Neutron transmission experiments can offer a new type of highly sensitive search for time-reversal invariance violating (TRIV) effects in nucleon-nucleon interactions via the same enhancement mechanism observed for large parity violating (PV) effects in neutron-induced compound nuclear processes. In these compound processes, the TRIV cross-section is given as the product of the PV cross-section, a spin-factor $$kappa$$, and a ratio of TRIV and PV matrix elements. We determined $$kappa$$ to be 0.59 $$pm$$ 0.05 for $$^{139}$$La+n using both (n, $$gamma$$) spectroscopy and ($$overrightarrow{n}$$+$$^{139}overrightarrow{textrm{La}}$$) transmission. This result quantifies for the first time the high sensitivity of the $$^{139}$$La 0.75 eV $$p$$-wave resonance in a future search for $$P$$-odd/$$T$$-odd interactions in ($$overrightarrow{n}$$+$$^{139}overrightarrow{textrm{La}}$$) forward transmission.

論文

Application of control software framework to sample environment equipment in J-PARC MLF

長谷美 宏幸; 高橋 竜太*; 山内 康弘*; 石角 元志*; 河村 聖子; 小峰 良太

JPS Conference Proceedings (Internet), 41, p.011003_1 - 011003_5, 2024/03

https://doi.org/10.7566/JPSCP.41.011003

The instrument control software framework "IROHA2" is used for the neutron and muon experiments at J-PARC MLF. IROHA2 consists of four core software components: i) The device control server controls and monitors devices, ii) the instrument management server authenticates users, manages measurements and configures device combinations, iii) the sequence management server builds and controls automatic measurements, iv) the integrate control server has centralized control over the device monitoring and measurement. Since IROHA2 is equipped with a web user interface, the control system can be accessed remotely using a web browser. MLF's sample environment team developed several device modules of the device control server in order to be able to use the sample environment equipment for automatic measurements. For example, the modules currently used in the experiments are those for $$^{3}$$He and $$^{4}$$He cryostats, superconducting magnets, niobium furnaces, and so on. In this presentation, we will introduce the features of IROHA2 and the functions of the device modules for the sample environment equipment.

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

https://doi.org/10.7566/JPSCP.38.011091

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

Possible future upgrades of the direct-geometry chopper spectrometer 4SEASONS

梶本 亮一; 中村 充孝; 蒲沢 和也*; 稲村 泰弘; 飯田 一樹*; 池内 和彦*; 石角 元志*

EPJ Web of Conferences, 272, p.02007_1 - 02007_8, 2022/11

https://doi.org/10.1051/epjconf/202227202007

4SEASONS is a direct geometry time-of-flight spectrometer installed in the Materials and Life Science Experimental Facility, the Japan Proton Accelerator Research Complex. It is used to study atomic andspin dynamics in the energy range of $$10^0$$ meV to $$10^2$$ meV. Since more than a decade has crossed after the first inelastic scattering experiment, it is essential to consider upgrading the instrument to improve its flexibility and performance. In this paper, we discuss the possible medium-term upgrades of key components of the instrument like the chopper system, which are achievable with the current technology and at reasonable cost. Herein, we demonstrated that 4SEASONS can improve the energy resolution by a factor of two, remove frame overlap of adjacent incident energies, significantly improve the asymmetry in the pulse shape, and increase the flux by a factor of $$sim$$1.5, without major technical difficulties.

論文

Energy resolution and neutron flux of the 4SEASONS spectrometer revisited

梶本 亮一; 中村 充孝; 飯田 一樹*; 蒲沢 和也*; 池内 和彦*; 稲村 泰弘; 石角 元志*

Journal of Neutron Research, 22(2-3), p.99 - 107, 2020/10

https://doi.org/10.3233/JNR-200146

The elastic energy resolution, integrated intensity, and peak intensity of the direct-geometry neutron chopper spectrometer 4SEASONS at Japan Proton Accelerator Research Complex (J-PARC) were re-investigated. This was done with respect to the incident energy and the rotation speed of the Fermi chopper using incoherent scattering of vanadium and simple analytical formulas. The model calculations reproduced the observed values satisfactorily. The present work should be useful for estimating in instrument performance in experiments.

論文

High-temperature short-range order in Mn$$_3$$RhSi

山内 宏樹; Sari, D. P.*; 渡邊 功雄*; 安井 幸夫*; Chang, L.-J.*; 近藤 啓悦; 伊藤 孝; 石角 元志*; 萩原 雅人*; Frontzek, M. D.*; et al.

Communications Materials (Internet), 1, p.43_1 - 43_6, 2020/07

https://doi.org/10.1038/s43246-020-0042-1

中性子とミュオンの相補利用により、720Kまでの高温での短距離磁気秩序現象をMn$$_3$$RhSiで発見した。

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

https://doi.org/10.1103/PhysRevB.101.220408
 被引用回数：26 パーセンタイル：79.23(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

Horizontal line nodes in Sr$$_2$$RuO$$_4$$ proved by spin resonance

飯田 一樹*; 古府 麻衣子; 鈴木 雄大*; 村井 直樹; 河村 聖子; 梶本 亮一; 稲村 泰弘; 石角 元志*; 長谷川 舜介*; 益田 隆嗣*; et al.

Journal of the Physical Society of Japan, 89(5), p.053702_1 - 053702_5, 2020/05

https://doi.org/10.7566/JPSJ.89.053702
 被引用回数：21 パーセンタイル：78.71(Physics, Multidisciplinary)

We investigated the low-energy incommensurate (IC) magnetic fluctuations in Sr$$_2$$RuO$$_4$$ by the high-resolution inelastic neutron scattering measurements and random phase approximation (RPA) calculations. We observed a spin resonance with energy of $$hbar omega_{rm res}0.56$$ meV centered at a characteristic wavevector $$Q_{rm res}=(0.3,0.3,0.5)$$. The resonance energy corresponds well to the superconducting gap 2$$Delta$$ = 0.56 meV estimated by the tunneling spectroscopy. The spin resonance shows the $$L$$ modulation with a maximum at around $$L = 0.5$$. The $$L$$ modulated intensity of the spin resonance and our RPA calculations indicate that the superconducting gaps regarding the quasi-one-dimensional $$alpha$$ and $$beta$$ sheets at the Fermi surfaces have the horizontal line nodes. These results may set a strong constraint on the pairing symmetry of Sr$$_2$$RuO$$_4$$. We also discuss the implications on possible superconducting order parameters.

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

https://doi.org/10.7566/JPSCP.30.011128

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

Crystal structures of highly hole-doped layered perovskite nickelate Pr$$_{2-x}$$Sr$$_{x}$$NiO$$_{4}$$ studied by neutron diffraction

梶本 亮一; 中島 健次; 藤田 全基*; 石角 元志*; 鳥居 周輝*; 石川 喜久*; Miao, P.*; 神山 崇*

Journal of the Physical Society of Japan, 88(11), p.114602_1 - 114602_6, 2019/11

https://doi.org/10.7566/JPSJ.88.114602
 被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)

A high-resolution time-of-flight powder neutron diffraction study of the layered nickel oxide Pr$$_{2-x}$$Sr$$_{x}$$NiO$$_{4}$$ with $$x = 0.7$$ and $$0.9$$ was performed to characterize the crystal structures of these highly hole-doped nickelates. For the sample with $$x = 0.7$$, the Ni-O bond lengths decrease uniformly with decreasing temperature, and the atomic displacement parameters are similar to those for $$x = 1/3$$. In contrast, for the sample with $$x = 0.9$$, the out-of-plane Ni-O bond length shows a sharp thermal contraction in the high-temperature region, which is suggestive of changes in the orbital occupation accompanied by the development of checkerboard-type charge correlations. Furthermore, the $$x = 0.9$$ sample is characterized by a large atomic displacement parameter for the apical O atoms along the out-of-plane direction, which is interpreted as the existence of two types of Ni$$^{3+}$$ sites with different orbital occupancies. The distinct difference between the $$x = 0.9$$ sample and the lower-concentration compounds should be related to the development of checkerboard-type charge ordering in the metallic matrix and possible orbital ordering at the Ni$$^{3+}$$ sites at $$x sim 1$$ in the hole-doped layered nickel oxides.

論文

Q dependence of magnetic resonance mode on FeTe$$_{0.5}$$Se$$_{0.5}$$ studied by inelastic neutron scattering

石角 元志*; 樹神 克明; 梶本 亮一; 中村 充孝; 稲村 泰弘; 池内 和彦*; Ji, S.*; 新井 正敏*; 社本 真一

Condensed Matter (Internet), 4(3), p.69_1 - 69_10, 2019/09

https://doi.org/10.3390/condmat4030069

中性子非弾性散乱により観測された磁気共鳴モードのQ依存性という初めての手法で、FeTe$$_{0.5}$$Se$$_{0.5}$$の超伝導対称性がs$$pm$$波であることを実験的に示した。

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

https://doi.org/10.1103/PhysRevB.100.014506
 被引用回数：39 パーセンタイル：84.23(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

Cryogenic sample environments shared at the MLF, J-PARC

河村 聖子; 高橋 竜太*; 石角 元志*; 山内 康弘*; 中村 雅俊*; 大内 啓一*; 吉良 弘*; 神原 理*; 青山 和弘*; 坂口 佳史*; et al.

Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05

https://doi.org/10.3233/JNR-190106

MLF試料環境チーム低温・マグネットグループは、J-PARC MLFにおいて、利用者の実験のための冷凍機やマグネットの運用を行っている。これまでトップローディング型$$^4$$He冷凍機、ボトムローディング型$$^3$$He冷凍機、希釈冷凍機インサート、超伝導マグネットを導入してきた。これらの機器の使用頻度は、ビーム出力、課題数の増加に伴い、ここ2年間で急激に高くなってきている。この状況に対応するために運用経験を加味しながら、これらの機器の性能向上作業を進めている。例えば、$$^3$$He冷凍機の制御ソフトには、自動の初期冷却および再凝縮のプログラムが備わっていたが、新たに、$$^3$$He potにヒーターを焚くことなくsorbの温度制御のみで$$^3$$He potを温調するプログラムも作成した。また2017年は、超伝導マグネット用に、揺動型ラジアルコリメーター付きのOVCテールを製作した。このラジアルコリメーターの導入によりデータの質は劇的に向上し、中性子非弾性散乱実験でも超伝導マグネットが使用できるようになった。

論文

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

梶本 亮一; 石角 元志*; 吉良 弘*; 金子 耕士; 中村 充孝; 蒲沢 和也*; 稲村 泰弘; 池内 和彦*; 飯田 一樹*; 村井 直樹; et al.

Physica B; Condensed Matter, 556, p.26 - 30, 2019/03

BB2018-0570.pdf:2.17MB

https://doi.org/10.1016/j.physb.2018.11.065
 被引用回数：3 パーセンタイル：8.82(Physics, Condensed Matter)

Magnets are important for studying magnetism and are commonly used as sample environment devices of neutron scattering instruments. However, the use of magnets was prevented at the time-of-flight direct-geometry neutron spectrometer 4SEASONS in Materials and Life Science Experimental Facility (MLF) at J-PARC, because the instrument is surrounded by iron components, and it is equipped with a piece of equipment operated with magnetic bearings. In the present work, we investigate the influence of stray magnetic fields from a superconducting magnet which is shared among neutron scattering instruments in MLF. Based on the investigation, we modified 4SEASONS such that it can be used with the magnet. Finally, we successfully performed the first inelastic neutron scattering experiments with applied magnetic fields using this sample environment.

論文

Quantum magnetisms in uniform triangular lattices Li$$_{2}$$$$A$$Mo$$_{3}$$O$$_{8}$$ ($$A$$ = In, Sc)

飯田 一樹*; 吉田 紘行*; 岡部 博孝*; 片山 尚幸*; 石井 裕人*; 幸田 章宏*; 稲村 泰弘; 村井 直樹; 石角 元志*; 門野 良典*; et al.

Scientific Reports (Internet), 9(1), p.1826_1 - 1826_9, 2019/02

https://doi.org/10.1038/s41598-018-36123-7
 被引用回数：13 パーセンタイル：64.91(Multidisciplinary Sciences)

Molecular based spin-1/2 triangular lattice systems have attracted research interest. Li$$_2$$$$A$$Mo$$_3$$O$$_8$$ ($$A$$ = In or Sc) is such a compound where spin-1/2 Mo$$_3$$O$$_{13}$$ clusters in place of Mo ions form the uniform triangular lattice. Here, we report exotic magnetisms in Li$$_2$$InMo$$_3$$O$$_8$$ and Li$$_2$$ScMo$$_3$$O$$_8$$ investigated by muon spin rotation ($$mu$$SR) and inelastic neutron scattering (INS) spectroscopies. Li$$_2$$InMo$$_3$$O$$_8$$ exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120$$^{circ}$$ spin structure. In contrast, Li$$_2$$ScMo$$_3$$O$$_8$$ undergoes short-range magnetic order below 4 K with quantum-spin-liquid-like magnetic fluctuations down to the base temperature. Origin of the different ground states is discussed in terms of anisotropies of crystal structures and magnetic interactions.

論文

Performances of oscillating radial collimator for the Fermi chopper spectrometer 4SEASONS at J-PARC

中村 充孝; 神原 理*; 飯田 一樹*; 梶本 亮一; 蒲沢 和也*; 池内 和彦*; 石角 元志*; 青山 和弘*

Physica B; Condensed Matter, 551, p.480 - 483, 2018/12

BB2017-0466.pdf:0.78MB

https://doi.org/10.1016/j.physb.2018.05.028
 被引用回数：7 パーセンタイル：27.16(Physics, Condensed Matter)

近年、磁場や圧力、高温といった特殊環境下での中性子非弾性散乱実験へのニーズが高まっており、質の高いデータを得るためには試料環境機器からの不要な散乱をできる限り低く抑える必要がある。そこで、我々はユーザーのニーズに応えるため、J-PARCのフェルミチョッパー分光器四季に特化した揺動型ラジアルコリメータを開発した。四季では比較的高い入射エネルギーを用いることから、コリメータのブレード素材に水素フリーの金属シートを採用した。このラジアルコリメータの制御システムでは、揺動スピードや揺動角等といった揺動パターンを柔軟に変更することが可能である。本稿では、新たに開発したラジアルコリメータの性能と残された課題について報告する。

論文

High-energy spin fluctuation in low-T$$_{c}$$ iron-based superconductor LaFePO$$_{0.9}$$

石角 元志*; 社本 真一; 樹神 克明; 梶本 亮一; 中村 充孝; Hong, T.*; Mutka, H.*

Scientific Reports (Internet), 8, p.16343_1 - 16343_6, 2018/11

https://doi.org/10.1038/s41598-018-33878-x
 被引用回数：3 パーセンタイル：26.94(Multidisciplinary Sciences)

磁気揺らぎはBCS理論に従わない非従来型超伝導で最も可能性のある機構として重要な役割を担うと考えられてきた。今回、これまで磁気ゆらぎが見つかっていない5Kという低い超伝導転移温度の鉄リン系超伝導体LaFePO$$_{0.9}$$で、30-50meVの高エネルギーで磁気ゆらぎを見つけた。これはこれまで考えられてきた高エネルギー磁気揺らぎで、高い超伝導転移温度になるという考えとは矛盾することから、超伝導機構の理解に向けて重要な発見である。

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