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Development and application of a $$^3$$He neutron spin filter at J-PARC

奥平 琢也; 奥 隆之; 猪野 隆*; 林田 洋寿*; 吉良 弘*; 酒井 健二; 廣井 孝介; 高橋 慎吾*; 相澤 一也; 遠藤 仁*; et al.

Nuclear Instruments and Methods in Physics Research A, 977, p.164301_1 - 164301_8, 2020/10

We are developing a neutron polarizer with polarized $$^3$$He gas, referred to as a $$^3$$He spin filter, based on the Spin Exchange Optical Pumping (SEOP) for polarized neutron scattering experiments at Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC). A $$^3$$He gas-filling station was constructed at J-PARC, and several $$^3$$He cells with long spin relaxation times have been fabricated using the gas-filling station. A laboratory has been prepared in the MLF beam hall for polarizing $$^3$$He cells, and compact pumping systems with laser powers of 30 W and 110 W, which can be installed onto a neutron beamline, have been developed. A $$^3$$He polarization of 85% was achieved at a neutron beamline by using the pumping system with the 110 W laser. Recently, the first user experiment utilizing the $$^3$$He spin filter was conducted, and there have been several more since then. The development and utilization of $$^3$$He spin filters at MLF of J-PARC are reported.


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*; 増田 隆嗣*; et al.

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

 被引用回数:0 パーセンタイル:100(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.


Phase-transition kinetics of magnetic skyrmions investigated by stroboscopic small-angle neutron scattering

中島 多朗*; 稲村 泰弘; 伊藤 崇芳*; 大石 一城*; 大池 広志*; 賀川 史敬*; 吉川 明子*; 田口 康二郎*; 加倉井 和久*; 十倉 好紀*; et al.

Physical Review B, 98(1), p.014424_1 - 014424_5, 2018/07

 被引用回数:4 パーセンタイル:58.39(Materials Science, Multidisciplinary)



Structure of the magnetic excitations in the spin-1/2 triangular-lattice Heisenberg antiferromagnet Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$

伊藤 沙也*; 栗田 伸之*; 田中 秀数*; 河村 聖子; 中島 健次; 伊藤 晋一*; 桑原 慶太郎*; 加倉井 和久*

Nature Communications (Internet), 8, p.235_1 - 235_6, 2017/08

 被引用回数:28 パーセンタイル:6.43(Multidisciplinary Sciences)

A spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) is a prototypical frustrated quantum magnet, which exhibits remarkable quantum many-body effects that arise from the synergy between spin frustration and quantum fluctuation. The ground-state properties of a spin-1/2 TLHAF are theoretically well understood. However, magnetic excitations are less well understood and the theoretical consensus is limited. The experimental study of the magnetic excitations in spin-1/2 TLHAFs has also been limited. Here we show the whole picture of magnetic excitations in the spin-1/2 TLHAF Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$ investigated by inelastic neutron scattering. Significantly different from the theory, the excitation spectra have a three-stage energy structure. The lowest first stage is composed of dispersion branches of single-magnon excitations. The second and third stages are dispersive continua accompanied by columnar continuum extending above 10 meV, which is six times larger than the exchange interaction J=1.67 meV. Our results indicate the necessity of a new theoretical framework.


Interaction of spin-orbital-lattice degrees of freedom; Vibronic state of the corner-sharing-tetrahedral frustrated spin system HoBaFe$$_{4}$$O$$_{7}$$ by dynamical Jahn-Teller effect

蒲沢 和也*; 石角 元志*; 河村 聖子; 川北 至信; 加倉井 和久*; 中島 健次; 佐藤 正俊*

Physical Review B, 95(10), p.104413_1 - 104413_7, 2017/03

 被引用回数:2 パーセンタイル:77.78(Materials Science, Multidisciplinary)

A powder inelastic neutron-scattering study of HoBaFe$$_{4}$$O$$_{7}$$ (HBFO) revealed characteristic magnetic excitations associated with geometrical spin frustration. Dispersionless excitations in energy ($$omega$$) and wave-vector ($$Q$$) space are observed at several discrete energies. Some of them can be attributed to crystal-field excitations of Ho$$^{3+}$$ in octahedral symmetry, but the others are explained instead by the vibronic state of the Fe$$^{2+}$$ dynamical Jahn-Teller effect with orbit-spin coupling, indicating interaction among the spin, the orbital, and the lattice degree of freedom. The antiferromagnetic HBFO lattice has cubic symmetry, and both Fe$$^{2+}$$ and Fe$$^{3+}$$ reside on corner-sharing tetrahedra with a number ratio of 3:1. Even though Fe$$^{2+}$$ is a Jahn-Teller active ion in tetrahedral symmetry, the system does not exhibit any static lattice distortion to the lowest temperature studied (4 K). The observed excitations can be understood by considering the dynamical interaction among spin-orbital-lattice degrees of freedom, indicating that spin fluctuation due to the frustration effect induces the dynamical Jahn-Teller effect, although in most cases a Jahn-Teller active ion Fe$$^{2+}$$ takes the static Jahn-Teller effect in a magnetic oxide system.


Neutron diffraction study of 1D quantum spin system Li$$_{2}$$ZrCuO$$_{4}$$ with incommensurate magnetic structure

安井 幸夫*; 井川 直樹; 加倉井 和久

JPS Conference Proceedings (Internet), 8, p.034012_1 - 034012_6, 2015/09

CuO$$_{2}$$リボン鎖を持つ擬一次元量子スピン系Li$$_{2}$$ZrCuO$$_{4}$$の磁気構造を中性子回折によって調べた。本物質は、およそ7Kにて反強磁性転移を示すが、この転移に伴って強誘電性が誘起されないという特徴を持つ。中性子粉末回折実験の結果、3KにてQ=(0, k, l$$pm$$0.488)および(h, 0, l$$pm$$0.488) (h, k and l=偶数)の超格子磁気反射が観測された。本報ではこれら中性子回折と磁性データから磁気構造を提案し、さらに本物質の反強磁性転移において強誘電性が誘起されない理由について議論する。


Development status of the NMR system for the polarized $$^{3}$$He Neutron Spin Filter (NSF) in the MLF at J-PARC

酒井 健二; 奥 隆之; 林田 洋寿*; 吉良 弘*; 廣井 孝介; 猪野 隆*; 大山 研二*; 大河原 学*; 加倉井 和久; 篠原 武尚; et al.

JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09

$$^{3}$$Heの中性子吸収断面積が強いスピン選択性を有することを利用した偏極$$^{3}$$Heフィルターは、ビーム調整が不要なため、ビームラインに設置すれば直ぐに使える簡便な中性子スピンフィルター(NSF)として利用できる。そのようなNSF実現のためには、NSFの$$^{3}$$He偏極度${it P}$を定常的にモニタするための核磁気共鳴(NMR)システムの開発が不可欠である。我々は断熱高速通過型(AFP)とパルス型NMRの特徴が相補的であることに着目して2つのシステムを併用した汎用性の高いNMRシステムを開発した。更に、J-PARCの中性子実験装置(BL10)での中性子透過率測定から得られた${it P}$で校正しながら、温度、パルスNMRの振動磁場の大きさや印可時間などの測定条件を変えて、AFPとパルスNMRの信号間の相関を測定した。例えば、パルスNMR測定に起因する減偏極率を0.1%以下になるまでパルスNMRの検出感度を小さくしても、2つのNMR信号間の線形性は確認できた。これらの結果から、我々は開発したNMRシステムが$$^{3}$$He偏極度モニタとして十分機能することを確認した。


Development of portable polarized $$^{3}$$He neutron spin filter and its application to magnetic field imaging at J-PARC

酒井 健二; 奥 隆之; 林田 洋寿; 吉良 弘*; 篠原 武尚; 及川 健一; 原田 正英; 加倉井 和久; 相澤 一也; 新井 正敏; et al.

Journal of Physics; Conference Series, 528, p.012016_1 - 012016_7, 2014/07

 被引用回数:0 パーセンタイル:100



Weak ferromagnetic ordering disordered by Rh$$^{3+}$$ ions for LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$

浅井 晋一郎*; 岡崎 竜二*; 寺崎 一郎*; 安井 幸夫*; 井川 直樹; 加倉井 和久

JPS Conference Proceedings (Internet), 3, p.014034_1 - 014034_6, 2014/06



Role of magnetic chirality in polarization flip upon a commensurate-incommensurate magnetic phase transition in YMn$$_{2}$$O$$_{5}$$

脇本 秀一; 木村 宏之*; 坂本 勇馬*; 福永 守*; 野田 幸男*; 武田 全康; 加倉井 和久

Physical Review B, 88(14), p.140403_1 - 140403_5, 2013/10

 被引用回数:17 パーセンタイル:33.7(Materials Science, Multidisciplinary)

We have performed simultaneous measurements of magnetic chirality by using polarized neutrons and electric polarization along the $$b$$-axis of single crystals of YMn$$^{4+}$$(Mn$$_{1-x}$$Ga$$_{x}$$)$$^{3+}$$O$$_{5}$$ with $$x=0.047$$ and $$0.12$$, in which nonmagnetic Ga-ions dilute Mn$$^{3+}$$ spins. Measurements conducted under zero field heating after various field-cooling conditions evidence that the magnetic chirality of Mn$$^{4+}$$ cycloidal spins plays a dominant role in the incommensurate magnetic (ICM) phase, whereas the magnetic exchange striction by the Mn$$^{4+}$$-Mn$$^{3+}$$ chain plays a dominant role in the commensurate magnetic (CM) phase. The polarization of YMn$$_{2}$$O$$_{5}$$ flips upon CM to ICM phase transition because the ferroelectricity driven by the magnetic chirality and the exchange striction provides opposite directions of polarization.


Effects of Mg, Ag, and Al substitutions on magnetic excitations in the triangular-lattice antiferromagnet CuCrO$$_{2}$$

梶本 亮一; 中島 健次; 河村 聖子; 稲村 泰弘; 加倉井 和久; 外園 貴久*; 大園 怜*; 奥田 哲治*

Journal of the Physical Society of Japan, 82(5), p.054702_1 - 054702_6, 2013/05

 被引用回数:4 パーセンタイル:60.52(Physics, Multidisciplinary)

Magnetic excitations in CuCrO$$_{2}$$, CuCr$$_{0.97}$$Mg$$_{0.03}$$O$$_{2}$$, Cu$$_{0.85}$$Ag$$_{0.15}$$CrO$$_{2}$$, and CuCr$$_{0.85}$$Al$$_{0.15}$$O$$_{2}$$ have been studied by powder inelastic neutron scattering to elucidate the element substitution effects on spin dynamics in the Heisenberg triangular-lattice antiferromagnet CuCrO$$_{2}$$. We found a variety of changes in the magnetic excitation spectra caused by the different types of the element substitutions. We argued that the origins of these changes in the magnetic excitations are the effects of doped holes or the change in dimensionality in magnetic correlations.


Magnetoelectric effect driven by magnetic domain modification in LuFe$$_{2}$$O$$_{4}$$

神戸 高志*; 深田 幸正*; 狩野 旬*; 永田 知子*; 岡崎 宏之*; 横谷 尚睦*; 脇本 秀一; 加倉井 和久; 池田 直*

Physical Review Letters, 110(11), p.117602_1 - 117602_5, 2013/03

 被引用回数:20 パーセンタイル:22.41(Physics, Multidisciplinary)

The magnetocapacitance effect was investigated using impedance spectroscopy on single crystals of LuFe$$_2$$O$$_4$$. The intrinsic impedance response could be separated from the interfacial response and showed a clear hysteresis loop below $$T_{rm Ferri} sim$$ 240 under the magnetic field. The neutron diffraction experiment under the magnetic field proves the origin of the dielectric property related to the motion of the nanosized ferromagnetic domain boundary. These results imply that the modification of the microscopic domain structure is responsible for the magnetoelectric effect in LuFe$$_2$$O$$_4$$.


Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ (x =0, 0.018)

中島 多朗*; 満田 節生*; 高橋 慶一郎*; 吉冨 啓祐*; 増田 一也*; 金子 周史*; 本間 勇紀*; 小林 悟*; 北澤 英明*; 小坂 昌史*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

We have investigated effects of applied uniaxial pressure ($$p$$) on magnetic phase transitions in a triangular lattice antiferromagnet CuFeO$$_{2}$$ (CFO) and a slightly Ga-substituted compound CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ (CFGO) with $$x$$ = 0.018. We have performed neutron diffraction, spherical neutron polarimetry, magnetic susceptibility and pyroelectric measurements under $$p$$ up to 100 MPa applied on the [1$$bar1$$0] surfaces of the single crystal samples.


Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ ($$x$$ = 0, 0.018)

中島 多朗*; 満田 節生*; 高橋 慶一郎*; 吉冨 啓祐*; 増田 一也*; 金子 周史*; 本間 勇紀*; 小林 悟*; 北澤 英明*; 小坂 昌史*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

 被引用回数:10 パーセンタイル:39.38(Physics, Multidisciplinary)

We have investigated effects of applied uniaxial pressure ($$p$$) on magnetic phase transitions in a triangular lattice antiferromagnet CuFeO$$_{2}$$ (CFO) and a slightly Ga-substituted compound CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ (CFGO) with $$x$$ = 0.018 by spherical neutron polarimetry. In both of CFO and CFGO ($$x$$ = 0.018), the application of $$p$$ significantly increases the transition temperature from the paramagnetic phase to a collinear incommensurate antiferromagnetic phase. This suggests that the application of $$p$$ breaks equilateral symmetry of the triangular lattice and partially relieves geometrical spin frustration, which generally suppresses long-range magnetic orderings. Thus we demonstrated that uniaxial pressure can be an effective tool to control magnetic phase transitions in frustrated magnets.


Higgs transition from a magnetic Coulomb liquid to a ferromagnet in Yb$$_{2}$$Ti$$_{2}$$O$$_{7}$$

Chang, L.-J.*; 小野田 繁樹*; Su, Y.*; Kao, Y.-J.*; Tsuei, K.-D.*; 安井 幸夫*; 加倉井 和久; Lees, M. R.*

Nature Communications (Internet), 3, p.992_1 - 992_7, 2012/08

 被引用回数:136 パーセンタイル:2.19(Multidisciplinary Sciences)

Experiments on dipolar spin ice have established a magnetic Coulomb phase where monopoles obey the magnetic Coulomb law. With quantum-mechanical interactions, these magnetic charges are carried by fractionalized bosonic quasi-particles, spinons, which can undergo Bose-Einstein condensation through a first-order transition via the Higgs mechanism. In this paper, we report evidence of a Higgs transition from a magnetic Coulomb liquid to a ferromagnet in single-crystal Yb$$_{2}$$Ti$$_{2}$$O$$_{7}$$. Polarised neutron scattering experiments show that the magnetic diffuse [111]-rod scattering and pinch-point features, typical features of magnetic Coulomb liquid phase, are suddenly suppressed below Tc $$sim$$ 0.21 K, where magnetic Bragg peaks and a full depolarisation of the neutron spins are observed with thermal hysteresis, indicating a first-order ferromagnetic transition. These experimental observations are explained from a quantum spin-ice model, whose high-temperature phase belongs to the magnetic Coulomb phase, while the ground state shows a nearly collinear ferromagnetism.


Development of polarized Xe gas target for neutron experiment at J-PARC

酒井 健二; 奥 隆之; 篠原 武尚; 吉良 弘; 大井 元貴; 前川 藤夫; 加倉井 和久; 猪野 隆*; 有本 靖*; 清水 裕彦*; et al.

Journal of Physics; Conference Series, 340, p.012037_1 - 012037_7, 2012/02

 被引用回数:2 パーセンタイル:33.68



Neutron scattering studies of the spin-5/2 antiferromagnetic linear trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

長谷 正司*; D$"o$nni, A.*; 小澤 清*; 北澤 英明*; 酒井 治*; Pomjakushin, V. Y.*; Keller, L.*; 金子 耕士; 目時 直人; 加倉井 和久; et al.

Journal of Physics; Conference Series, 340, p.012066_1 - 012066_7, 2012/00

 被引用回数:1 パーセンタイル:51.44

スピン5/2反強磁性Mn量子トリマーの[0, $$k_y$$, 0]インコメンシュレート構造($$k_y$$=0.316-0.331)を中性子粉末回折により明らかにし、$$T_{rm N2}=1.75(5)$$Kにおいて波数が急激に替わることから磁気秩序層が二つ存在することを明らかにした。非弾性散乱実験によって観察された分散を示さない励起(0.46, 0.68, and 1.02meV)が、この系の磁気励起が反強磁性量子トリマーモデルで説明できることを明らかにした。解析によって、量子トリマー形成に重要な最近接相互作用$$J$$$$_1$$=0.29meVが半強磁性的であることを明らかにした。


Magnetic excitations in the spin-5/2 antiferromagnetic trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

長谷 正司*; 松田 雅昌*; 金子 耕士; 目時 直人; 加倉井 和久; Yang, T.*; Cong, R.*; Lin, J.*; 小澤 清*; 北澤 英明*

Physical Review B, 84(21), p.214402_1 - 214402_6, 2011/12

 被引用回数:9 パーセンタイル:55.13(Materials Science, Multidisciplinary)

A quantum-mechanical 1/3 magnetization plateau and magnetic long-range order appear in the large-spin (5/2) substance SrMn$$_{3}$$P$$_{4}$$O$$_{14}$$. Previous magnetization results suggest that the spin system consists of antiferromagnetic trimers that are weakly coupled with one another. We inferred that the magnetization plateau originated from discrete energy levels of the trimer. In order to confirm the discrete energy levels, we performed inelastic neutron scattering experiments on SrMn$$_{3}$$P$$_4$$O$$_{14}$$ powders. Observed magnetic excitations are consistent with excitations expected in the trimer model.


Neutron scattering of iron-based superconductors

社本 真一; 脇本 秀一; 樹神 克明; 石角 元志; Christianson, A. D.*; Lumsden, M. D.*; 梶本 亮一; 中村 充孝; 稲村 泰弘; 新井 正敏; et al.

Physica C, 471(21-22), p.639 - 642, 2011/11

 被引用回数:0 パーセンタイル:100(Physics, Applied)



ToF inelastic neutron scattering studies on quantum spin systems (CuCl)La$$B_2$$O$$_7$$ ($$B$$ = Nb, Ta)

河村 聖子; 中島 健次; 稲村 泰弘; 辻本 吉廣*; 北田 敦*; 竹入 史隆*; 陰山 洋*; 網代 芳民*; 西 正和*; 加倉井 和久

Journal of Physics; Conference Series, 320, p.012037_1 - 012037_5, 2011/09

 被引用回数:0 パーセンタイル:100

(CuCl)LaNb$$_2$$O$$_7$$の磁気基底状態はギャップ$$Delta E sim 2.3$$meVを持つスピン1重項状態であることが提唱されており、一方(CuCl)LaTa$$_2$$O$$_7$$は反強磁性秩序を基底状態に持つ。これらの系は、最近接及び次近接の交換相互作用の競合によりフラストレートした量子スピン系としてふるまうことが示唆されている。われわれは、ToF中性子非弾性散乱法を用いて、これらの系における磁気励起の研究を行ってきた。測定は、J-PARCに設置されたディスクチョッパー型分光器アマテラスを用いて、(CuCl)LaNb$$_2$$O$$_7$$及び(CuCl)LaTa$$_2$$O$$_7$$粉末試料に対して行った。両試料において、バンド状の励起が、$$Delta E sim 2$$meV近傍で観測された。(CuCl)LaNb$$_2$$O$$_7$$については、観測された2meV周辺での磁気励起の積分強度の$$Q$$依存性は3軸分光器で観測された結果をよく再現しており、スピン1重項ダイマーの性質を示している。一方、反強磁性相における(CuCl)LaTa$$_2$$O$$_7$$は、それとは異なる$$Q$$依存性を示した。

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