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論文

Impact of the Ce states in the electronic structure of the intermediate-valence superconductor CeIr

藤森伸一; 川崎郁斗; 竹田幸治; 山上浩志; 雀部矩正*; 佐藤芳樹*; 清水悠晴*; 仲村愛*; Maruya, A.*; 本間佳哉*; et al.

Electronic Structure (Internet), 5(4), p.045009_1 - 045009_7, 2023/11

https://doi.org/10.1088/2516-1075/ad0a3d

The electronic structure of the -based superconductor $mathrm{CeIr_3}$ was studied by photoelectron spectroscopy. The energy distribution of the state was revealed by the resonant photoelectron spectroscopy. The state was mostly distributed in the vicinity of the Fermi energy, suggesting the itinerant character of the state. The contribution of the state to the density of states (DOS) at the Fermi energy was estimated to be nearly half of that of the states, implying that the state has aconsiderable contribution to the DOS at the Fermi energy. The core-level and X-ray absorption spectra were analyzed based on a single-impurity Anderson model. The number of the state in the ground state was estimated to be 0.8-0.9, which is much larger than the values obtained in the previous studies (i.e., 0-0.4).

論文

Magnetic and fermi surface properties of semimetals EuAs and Eu(As $_{1-x}$ P)

大貫惇睦*; 軽部皓介*; 青木大*; 仲村愛*; 本間佳哉*; 松田達磨*; 芳賀芳範; 竹内徹也*

Journal of the Physical Society of Japan, 92(11), p.114703_1 - 114703_12, 2023/11

https://doi.org/10.7566/JPSJ.92.114703

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

Single crystal samples of a series of semimetallic magnet Eu(As $_{1-x}$ P) have successfully grown. By measuring magnetization, Hall resistivity and de Haas-van Alphen oscillations, large anomalous Hall resistivity arising from peculiar magnetic phase diagram was identified.

論文

Superconducting spin reorientation in spin-triplet multiple superconducting phases of UTe

金城克樹*; 藤林裕己*; 松村拓輝*; 堀文哉*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; et al.

Science Advances (Internet), 9(30), p.2736_1 - 2736_6, 2023/07

https://doi.org/10.1126/sciadv.adg2736

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

Superconducting (SC) state has spin and orbital degrees of freedom, and spin-triplet superconductivity shows multiple SC phases because of the presence of these degrees of freedom. However, the observation of spin-direction rotation occurring inside the SC state (SC spin rotation) has hardly been reported. Uranium ditelluride, a recently found topological superconductor, exhibits various SC phases under pressure: SC state at ambient pressure (SC1), high-temperature SC state above 0.5 gigapascal (SC2), and low-temperature SC state above 0.5 gigapascal (SC3). We performed nuclear magnetic resonance (NMR) and ac susceptibility measurements on a single-crystal uranium ditelluride. The b axis spin susceptibility remains unchanged in SC2, unlike in SC1, and decreases below the SC2-SC3 transition with spin modulation. These unique properties in SC3 arise from the coexistence of two SC order parameters. Our NMR results confirm spin-triplet superconductivity with SC spin parallel to b axis in SC2 and unveil the remaining of spin degrees of freedom in SC uranium ditelluride.

論文

Low-temperature magnetic fluctuations investigated by $^{125}$ Te-NMR on the uranium-based superconductor UTe

藤林裕己*; 金城克樹*; 仲嶺元輝*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; 清水悠晴*; et al.

Journal of the Physical Society of Japan, 92(5), p.053702_1 - 053702_5, 2023/05

https://doi.org/10.7566/JPSJ.92.053702

被引用回数：2 パーセンタイル：80.44(Physics, Multidisciplinary)

To investigate the static and dynamic magnetic properties on the uranium-based superconductor UTe, we measured the NMR Knight shift and the nuclear spin lattice relaxation rate 1/ in by $^{125}$ Te-NMR on a $^{125}$ Te-enriched single-crystal sample. 1/ in is much smaller than 1/ in and c, and magnetic fluctuations along each axis are derived from the 1/ measured in parallel to all three crystalline axes. The magnetic fluctuations are almost identical at two Te sites and isotropic at high temperatures, but become anisotropic below 40 K, where heavy-fermion state is formed.

論文

Large reduction in the -axis knight shift on UTe with = 2.1 K

松村拓輝*; 藤林裕己*; 金城克樹*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; 清水悠晴*; et al.

Journal of the Physical Society of Japan, 92(6), p.063701_1 - 063701_5, 2023/05

https://doi.org/10.7566/JPSJ.92.063701

被引用回数：5 パーセンタイル：92.42(Physics, Multidisciplinary)

Spin susceptibility in the superconducting (SC) state was measured in the higher-quality sample of uranium-based superconductor UTe by using Knight-shift measurements for a magnetic field along all three crystalline axes. In the higher-quality sample, the SC transition temperature is about 2.1 K, and the residual electronic term in the specific heat is almost zero. The NMR linewidth becomes narrower and is almost half of that in the previous sample with 1.6 K when and . Although the Knight-shift behavior was not so different from the previous results for , and , a large reduction in Knight shift along the axis was observed, in contrast with the previous -axis Knight shift result. We discuss the origin of the difference between the previous and present results, and the possible SC state derived from the present results.

論文

Magnetic properties of single crystalline TbSb

北折暁*; 金澤直也*; 木田孝則*; 鳴海康雄*; 萩原政幸*; 金道浩一*; 竹内徹也*; 仲村愛*; 青木大*; 芳賀芳範; et al.

Journal of the Physical Society of Japan, 92(2), p.024702_1 - 024702_6, 2023/02

https://doi.org/10.7566/JPSJ.92.024702

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

Magnetic properties of TbSb are reported. Unlike previous investigations on a polycrystal showing multiple phase transitions, the present single crystal sample shows a single transition 133 K. It is also shown that the magnetic hysteresis increases at low temperatures.

論文

Change of superconducting character in UTe $_{2}$ induced by magnetic field

金城克樹*; 藤林裕己*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; 清水悠晴*; 本間佳哉*; et al.

Physical Review B, 107(6), p.L060502_1 - L060502_5, 2023/02

https://doi.org/10.1103/PhysRevB.107.L060502

被引用回数：7 パーセンタイル：93.16(Materials Science, Multidisciplinary)

UTe is a recently discovered spin-triplet superconductor. One of the characteristic features of UTe is a magnetic field ()-boosted superconductivity above 16 T when H is applied exactly parallel to the axis. To date, this superconducting (SC) state has not been thoroughly investigated, and the SC properties as well as the spin state of this high- SC (HHSC) phase are not well understood. In this letter, we performed AC magnetic susceptibility and nuclear magnetic resonance measurements and found that, up to 24.8 T, the HHSC state has bulk nature and is quite sensitive to the angle and that its SC character is different from that in the low- SC (LHSC) state. The dominant spin component of the spin-triplet pair is along the axis in the LHSC state but is changed in the HHSC state along the axis. Our results indicate that -induced multiple SC states originate from the remaining spin degrees of freedom.

論文

First observation of the de Haas-van Alphen effect and Fermi surfaces in the unconventional superconductor UTe

青木大*; 酒井宏典; Opletal, P.; 常盤欣文; 石塚淳*; 柳瀬陽一*; 播磨尚朝*; 仲村愛*; Li, D.*; 本間佳哉*; et al.

Journal of the Physical Society of Japan, 91(8), p.083704_1 - 083704_5, 2022/08

https://doi.org/10.7566/JPSJ.91.083704

被引用回数：22 パーセンタイル：96.09(Physics, Multidisciplinary)

de Haas-van Alphen oscillation was successfully observed in an unconventional superconductor UTe using high-quality single crystals. From this observation, Fermi surfaces of this compound were determined to be cylinders elongated along the c-direction, in consistent with theoretical expectation. However, the extremely large cyclotron effective masses ranging 32 to 57 m, in consistent with the electronic specific heat, far exceed calculated values.

論文

Single crystal growth and magnetic properties of -Mn and -Mn

大貫惇睦*; 青木大*; 仲村愛*; 松田達磨*; 中島美帆*; 芳賀芳範; 竹内徹也*

Journal of the Physical Society of Japan, 91(6), p.065001_1 - 065001_2, 2022/06

https://doi.org/10.7566/JPSJ.91.065001

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

Single crystals of -Mn and -Mn are successfully grown. Non-Fermi-liquid relations of the low-temperature resistivity and specific heat are found in the spin-liquid state of -Mn. On the other hand, -Mn exhibits antiferromagnetic transition.

論文

Single crystal growth and magnetic properties of noncentrosymmetric antiferromagnet MnIrSi

大貫惇睦*; 金子良夫*; 青木大*; 仲村愛*; 松田達磨*; 中島美帆*; 芳賀芳範; 竹内徹也*

Journal of the Physical Society of Japan, 91(6), p.065002_1 - 065002_2, 2022/06

https://doi.org/10.7566/JPSJ.91.065002

被引用回数：2 パーセンタイル：28(Physics, Multidisciplinary)

Single crystals of MnIrSi were grown using Bridgman method. MnIrSi shows a remarkable increase of the electrical resistivity below antiferromagnetic transition temperature accompanied by a large jump of specific heat.

論文

Split Fermi surface properties of noncentrosymmetric compounds FeP, NiP, and PdSi

大貫惇睦*; 仲村愛*; 青木大*; 松田達磨*; 芳賀芳範; 播磨尚朝*; 竹内徹也*; 金子良夫*

Journal of the Physical Society of Japan, 91(6), p.064712_1 - 064712_10, 2022/06

https://doi.org/10.7566/JPSJ.91.064712

被引用回数：1 パーセンタイル：28(Physics, Multidisciplinary)

Fermi surface of noncentrocymmetric FeP, NiP and PdSi was studied by means of de Haas-van Alphen experiments. The splitting energy of Fermi surfaces due to antisymmetric spin-orbit coupling is estimated.

論文

Drastic change in magnetic anisotropy of UTe under pressure revealed by $^{125}$ Te-NMR

金城克樹*; 藤林裕己*; 仲嶺元輝*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; 清水悠晴*; et al.

Physical Review B, 105(14), p.L140502_1 - L140502_5, 2022/04

https://doi.org/10.1103/PhysRevB.105.L140502

被引用回数：5 パーセンタイル：67.2(Materials Science, Multidisciplinary)

To investigate the normal-state magnetic properties of UTe under pressure, we perform $^{125}$ Te nuclear magnetic resonance (NMR) measurements up to 2 GPa. Below 1.2 GPa, the b-axis NMR Knight shift shows a broad maximum at the so-called $T_{chi, max}$ on cooling, which is consistent with the magnetization measurement under pressure. $T_{chi, max}$ decreases with increasing pressure and disappears at the critical pressure = 1.7 GPa, above which superconductivity is destroyed.

論文

Slow electronic dynamics in the paramagnetic state of UTe

徳永陽; 酒井宏典; 神戸振作; 芳賀芳範; 常盤欣文; Opletal, P.; 藤林裕己*; 金城克樹*; 北川俊作*; 石田憲二*; et al.

Journal of the Physical Society of Japan, 91(2), p.023707_1 - 023707_5, 2022/02

https://doi.org/10.7566/JPSJ.91.023707

被引用回数：14 パーセンタイル：93.17(Physics, Multidisciplinary)

ウラン系の強磁性超伝導体で議論されてきた、「強磁性ゆらぎによるスピン三重項超伝導対の形成」および「強磁性ゆらぎを介した磁場による対形成引力の制御」というコンセプトがUTeにおいても成り立つことを期待させる。しかしその一方、では静的な強磁性秩序は存在せず、低温の磁気状態がこれまでのウラン系強磁性超伝導体にどこまで近いのかという点については疑問を持たれていた。実際、最近の中性子散乱実験では、比較的高温側から反強磁性に近いq=0.57という波数を持った磁気ゆらぎの発達が示されている。本研究では $^{125}$ Te-NMR実験により低温で非常に遅いゆっくりとした揺らぎが発達する様子を捉えることに成功した。このことはこの系の低温における強い相関の発達を示唆している。

論文

Observation of longitudinal magnetic fluctuations at a first-order ferromagnetic quantum phase transition in UGe

野間雄一郎*; 小手川恒*; 久保徹郎*; 藤秀樹*; 播磨尚朝*; 芳賀芳範; 山本悦嗣; 大貫惇睦*; 伊藤公平*; 仲村愛*; et al.

Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07

https://doi.org/10.7566/JPSJ.90.073707

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

Ferromagnetic fluctuation relevant to the pressure-induced superconductivity in UGe is investigated by means of NMR spectroscopy. Longitudinal magnetic fluctuations were observed in the spin-echo decay rate near the ferromagnetic critical point where superconductivity takes place. This result strongly suggests that superconductivity in ferromagnets is universally mediated by anisotropic magnetic fluctuations.

論文

Critical slowing-down and field-dependent paramagnetic fluctuations in the skyrmion host EuPtSi; SR and NMR studies

比嘉野乃花*; 伊藤孝; 與儀護*; 服部泰佑; 酒井宏典; 神戸振作; Guguchia, Z.*; 髭本亘; 中島美帆*; 本間佳哉*; et al.

Physical Review B, 104(4), p.045145_1 - 045145_7, 2021/07

https://doi.org/10.1103/PhysRevB.104.045145

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

We report the results of SR and $^{29}$ Si NMR measurements carried out on the cubic chiral magnet EuPtSi. Our zero-field SR experiments revealed the development of critical slowing down of Eu spin fluctuations over a relatively wide critical region above . We also found from $^{29}$ Si NMR that the spin fluctuations are strongly suppressed by magnetic field in the paramagnetic state above 20K. These characteristic spin dynamics observed over a wide region of temperature and magnetic field suggest the presence of magnetic frustration in the spin system. Such frustration would underlie the mechanism stabilizing the short-period skyrmion lattice observed in this compound.

論文

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

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

https://doi.org/10.7566/JPSJ.90.064704

被引用回数：37 パーセンタイル：95.85(Physics, Multidisciplinary)

Multiple transition phenomena in divalent Eu compound EuAl 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 ). Considering an absence of splitting in magnetic peaks along , the structural transition is mainly ascribed to a displacement of Al ions within the tetragonal -plane. Complex incommensurate magnetic transitions are in stark contrast to a simple collinear commensurate structure in isovalent EuGa. This could stem from incompatible electronic structures with the CDW transition between two compounds.

論文

Inhomogeneous superconducting state probed by $^{125}$ Te NMR on UTe

仲嶺元輝*; 金城克樹*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; 清水悠晴*; 本間佳哉*; et al.

Journal of the Physical Society of Japan, 90(6), p.064709_1 - 064709_7, 2021/06

https://doi.org/10.7566/JPSJ.90.064709

被引用回数：17 パーセンタイル：85.26(Physics, Multidisciplinary)

UTe is a recently discovered promising candidate for a spin-triplet superconductor. In contrast to conventional spin-singlet superconductivity, spin-triplet superconductivity possesses spin and angular momentum degrees of freedom. We previously reported that the shoulder signal appears in NMR spectra below the superconducting (SC) transition temperature in , and a slight decrease in the Knight shift along the and axes ( $K_{rm b}$ and $K_{rm c}$ , respectively) below at a low magnetic field . Although the decrease in $K_{rm c}$ vanished above 5.5 T, the decrease in $K_{rm b}$ was independent of up to 6.5 T. To clarify the origin of the shoulder signal and the trace of the decrease in $K_{rm b}$ , we compared the $^{125}$ Te-NMR spectra obtained when and and measured the $^{125}$ Te-NMR spectra for up to 14.5 T.

論文

Anisotropic response of spin susceptibility in the superconducting state of UTe probed with $^{125}$ Te-NMR measurement

仲嶺元輝*; 金城克樹*; 北川俊作*; 石田憲二*; 徳永陽; 酒井宏典; 神戸振作; 仲村愛*; 清水悠晴*; 本間佳哉*; et al.

Physical Review B, 103(10), p.L100503_1 - L100503_5, 2021/03

https://doi.org/10.1103/PhysRevB.103.L100503

被引用回数：32 パーセンタイル：93.31(Materials Science, Multidisciplinary)

To investigate spin susceptibility in a superconducting (SC) state, we measured the $^{125}$ Te-NMR Knight shifts at magnetic fields () up to 6.5 T along the and axes of single-crystal UTe, a promising candidate for a spin-triplet superconductor. In the SC state, the Knight shifts along the and axes ( $K_{rm b}$ and $K_{rm c}$ , respectively) decreased slightly, and the decrease in $K_{rm b}$ was almost constant up to 6.5 T. The reduction in $K_{rm c}$ decreased with increasing , and $K_{rm c}$ was unchanged through the SC transition temperature at 5.5 T, excluding the possibility of spin-singlet pairing. Our results indicate that spin susceptibilities along the and axes slightly decrease in the SC state in low , and the response of SC spin susceptibility is anisotropic on the plane.

論文

Single-crystal growth and magnetic phase diagram of the enantiopure crystal of NdPtB

佐藤芳樹*; 本多史憲*; Maurya, A.*; 清水悠晴*; 仲村愛*; 本間佳哉*; Li, D.*; 芳賀芳範; 青木大*

Physical Review Materials (Internet), 5(3), p.034411_1 - 034411_9, 2021/03

https://doi.org/10.1103/PhysRevMaterials.5.034411

被引用回数：1 パーセンタイル：6.33(Materials Science, Multidisciplinary)

Single-crystal growth and magnetic properties of NdPtB are reported on a enantiopure crystal. We observed multiple phase transitions at 9.5 and 11 K under zero magnetic field. Nontrivial magnetic phase diagram demonstrates the competitive interactions in this system.

論文

Core-level photoelectron spectroscopy study of UTe $_{2}$

藤森伸一; 川崎郁斗; 竹田幸治; 山上浩志; 仲村愛*; 本間佳哉*; 青木大*

Journal of the Physical Society of Japan, 90(1), p.015002_1 - 015002_2, 2021/01

https://doi.org/10.7566/JPSJ.90.015002

被引用回数：12 パーセンタイル：79.44(Physics, Multidisciplinary)

The valence state of $mathrm{UTe}_2$ was studied by core-level photoelectron spectroscopy. The main peak position of the core-level spectrum of $mathrm{UTe}_2$ coincides with that of $mathrm{UB}_2$ , which is anitinerant compound with a nearly configuration. However, the main peak of $mathrm{UTe}_2$ is broader than that of $mathrm{UB}_2$ , and satellite structures are observed in the higher binding energy side of the main peak, which are characteristics of mixed-valence uranium compounds. These results suggest that the state in $mathrm{UTe}_2$ isin a mixed valence state with a dominant contribution from the itinerant configuration.