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森 道康
Journal of the Physical Society of Japan, 89(11), p.114705_1 - 114705_7, 2020/11
被引用回数:0The nuclear magnetic relaxation time in a ferrimagnetic insulators is calculated within the mean-field approximation for the magnetic exchange interactions and the Raman process involving the hyperfine interaction. We find that the value of 1/
on one type of site increases rapidly near the compensation temperature
, whereas that on the other type of site does not increase up to Curie temperature
. This is due to the fact that the soft-magnon bandwidth becomes comparable to
. An increase in 1/
below
is found also in another type ferrimagnet, which shows a hump structure in the temperature dependence of magnetization instead of compensation. Also in that case, we find the rapid increase in 1/
below
, even though the magnetization does not show compensation. The coexistence of soft and hard magnons leads to these remarkable properties of ferrimagnets.
山本 慧; Yu, W.*; Yu, T.*; Puebla, J.*; Xu, M.*; 前川 禎通*; Bauer, G.*
Journal of the Physical Society of Japan, 89(11), p.113702_1 - 113702_5, 2020/11
被引用回数:0We predict that surface acoustic waves are generated preferentially in one direction in a heterostructure of a thin magnetic film on a non-magnetic substrate. The non-reciprocity arises from magneto-elastic coupling and magneto-rotation coupling, the former being dominant for YIG/GGG heterostructures. For YIG films thinner than about 100 nm, the surface acoustic wave amplitude is nearly unidirectional at certain angles of the in-plane equilibrium magnetisation. We compute the full magnetic field dependence of the effect for a selected device.
佐藤 研太朗*; 池内 和彦*; 梶本 亮一; 脇本 秀一; 新井 正敏*; 藤田 全基*
Journal of the Physical Society of Japan, 89(11), p.114703_1 - 114703_7, 2020/11
被引用回数:0To elucidate the spin dynamics of LaSr
CuO
, which couples with the charge degree of freedom, the spin excitations spanning the characteristic energy (
35--40 meV) are investigated for underdoped
= 0.10 and optimally doped (OP)
= 0.16 through inelastic neutron scattering measurements. Analysis based on a two-component picture of high-quality data clarified the possible coexistence of upright standing incommensurate (IC) excitations with gapless commensurate (C) excitations in the energy-momentum space. The IC component weakens the intensity toward
with increasing energy transfer (
), whereas the C component strengthens at high-
regions. The analysis results imply that the superposition of two components with a particular intensity balance forms an hourglass-shaped excitation in appearance. Furthermore, the temperature dependence of the intensity of each component exhibits different behaviors; the IC component disappears near the pseudo-gap temperature (
) upon warming, whereas the C component is robust against temperature. These results suggest the itinerant electron spin nature and the localized magnetism of the parent La
CuO
in IC and C excitations, respectively, similar to the spin excitations in the OP YBa
Cu
O
and HgBa
CuO
with higher superconducting-transition temperatures.
古府 麻衣子; 山室 修*
Journal of the Physical Society of Japan, 89(5), p.051002_1 - 051002_12, 2020/05
被引用回数:1 パーセンタイル:30.13(Physics, Multidisciplinary)金属中の水素の挙動は、基礎および応用研究の広い領域で古くから興味がもたれてきた。金属の中でもパラジウムは特別である。パラジウムは大量の水素を吸収し、またパラジウムのfcc格子中を水素は自由に拡散する。中性子分光は水素原子の微視的ダイナミクスを調べる最適な手法であり、パラジウム中の水素のダイナミクスが精力的に研究されてきた。本論文では、研究初期から最新のパラジウム水素化物の中性子散乱研究をレビューし、バルクおよびナノサイズのパラジウム中の水素ダイナミクスがどのように理解されているか示す。
伊藤 孝; 髭本 亘; 下村 浩一郎*
Journal of the Physical Society of Japan, 89(5), p.051007_1 - 051007_8, 2020/05
被引用回数:1 パーセンタイル:100(Physics, Multidisciplinary)Muonium (Mu) centers formed upon implantation of in a solid have long been investigated as an experimentally accessible model of isolated hydrogen impurities. Recent discoveries of hydridic centers formed at oxygen vacancies have stimulated a renewed interest in H
and corresponding Mu
centers in oxides. However, the two diamagnetic centers, Mu
and Mu
, are difficult to separate spectroscopically. In this review article, we summarize established and developing methodologies for identifying Mu
centers in solids, and review recent Mu studies on said centers supposedly formed in mayenite, oxygen-deficient SrTiO
, and BaTiO
H
oxyhydride.
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:2 パーセンタイル:14.51(Physics, Multidisciplinary)We investigated the low-energy incommensurate (IC) magnetic fluctuations in SrRuO
by the high-resolution inelastic neutron scattering measurements and random phase approximation (RPA) calculations. We observed a spin resonance with energy of
meV centered at a characteristic wavevector
. The resonance energy corresponds well to the superconducting gap 2
= 0.56 meV estimated by the tunneling spectroscopy. The spin resonance shows the
modulation with a maximum at around
. The
modulated intensity of the spin resonance and our RPA calculations indicate that the superconducting gaps regarding the quasi-one-dimensional
and
sheets at the Fermi surfaces have the horizontal line nodes. These results may set a strong constraint on the pairing symmetry of Sr
RuO
. We also discuss the implications on possible superconducting order parameters.
川崎 郁斗; 小畠 雅明; 藤森 伸一; 竹田 幸治; 山上 浩志; 仲村 愛*; 伊覇 航*; 辺土 正人*; 仲間 隆男*; 大貫 惇睦*
Journal of the Physical Society of Japan, 89(4), p.044704_1 - 044704_6, 2020/04
被引用回数:1 パーセンタイル:30.13(Physics, Multidisciplinary)EuPd is a rare Eu-based compound, whose Eu ions are in a trivalent state. The electronic structure of EuPd
was investigated by angle-resolved photoemission spectroscopy (ARPES) using soft X rays. Eu
components arising from the 4f
final state multiplet were clearly observed in the valence spectra, and no Eu
components were observed within an experimental accuracy, confirming a robust Eu
state. The band structure and Fermi surfaces revealed by ARPES measurements were compared to the band structure calculations based on the density-functional theory for LaPd
andYPd
. We found that the calculation for LaPd
provides a better description for our ARPES results. The effective electron masses estimated from the ARPES spectra near the Fermi level are in good agreement with the corresponding cyclotron effective masses in previous de Haas-van Alphen experiments.
塚田 和明; 永井 泰樹*; 橋本 慎太郎; 湊 太志; 川端 方子*; 初川 雄一*; 橋本 和幸*; 渡辺 智*; 佐伯 秀也*; 本石 章司*
Journal of the Physical Society of Japan, 89(3), p.034201_1 - 034201_7, 2020/03
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)ポリエチレン遮へい中のZnOに、50MeV重陽子と
Beによる(
)反応で生成した中性子を照射することで、
Ga,
Ga,
Zn、並びに
Cuの特異な生成を実験的に確認した。特に、ポリエチレン遮へい内で得られた収率は、遮へいなしの実験と比較して、約20倍の収量を示した。一方、鉛遮へい内の金属
Zn試料の照射における
Ga,
Ga,
Zn、並びに
Cuの収量と、
ZnO及び金属
Zn試料の照射における
Cu,
Ni及び
Znの収量は、遮へいによる影響はほとんど受けていない。この実験結果は、遮へい条件を調整することで、中性子反応に限らず陽子反応を含む多様で大量の放射性同位元素を、一度の照射で同時に合成できるという加速器中性子の注目すべき特性を示すものである。また、PHITSコードを利用した生成量予測を試み、本実験結果と比較することで、本生成量の特異性について評価した。
竹内 徹也*; 芳賀 芳範; 谷口 年史*; 伊覇 航*; 安次富 洋介*; 屋良 朝之*; 木田 孝則*; 田原 大夢*; 萩原 政幸*; 中島 美帆*; et al.
Journal of the Physical Society of Japan, 89(3), p.034705_1 - 034705_15, 2020/03
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)Single crystals of EuCuSi
have been grown by the flux method and Bridgman method. The Eu ions of the Bridgman-grown crystal are nearly trivalent and fluctuate depending on the temperature. On the other hand, the Eu ions of flux-grown sample are divalent and thermally stable and show spin-glass behavior at low temperatures. Crystallographic analyses identified random replacement of Cu sites by Si only for the flux-grown samples. Such structural randomness leads to spin-glass features.
駒淵 舞*; 漆原 大典*; 浅香 透*; 福田 功一郎*; 大原 高志; 宗像 孝司*; 石川 喜久*
Journal of the Physical Society of Japan, 89(3), p.034601_1 - 034601_5, 2020/03
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)The crystal structure of an X-type hexaferrite SrCo
Fe
O
was investigated by the X-ray and neutron diffraction methods for a single crystal. Sr
Co
Fe
O
has the crystal structure described as a space group
(
) and its lattice constants are
= 5.9165(2)
; and
= 84.1395(33)
; at 843 K. Co ions are almost localized in the octahedral site (
) in the middle of S
S
blocks. In addition, the adjacent octahedral and tetrahedral sites to
site contain the significant number of Co
.
目時 直人; 青木 大*; Griveau, J.-C.*; 大槻 純也*
Journal of the Physical Society of Japan, 89(2), p.024707_1 - 024707_6, 2020/02
被引用回数:2 パーセンタイル:14.51(Physics, Multidisciplinary)重い電子系超伝導体NpPdAl
の擬三重項5
電子基底状態を明らかにした。主に
からなる一重項基底状態
の
,K上に、
が主要な成分の二重項第一励起状態
を仮定することで帯磁率の温度依存性が説明できる。磁化曲線は擬スピン
=1の局所有効ハミルトニアン
(
)で説明でき、これは四極子演算子
と等価である。比熱は擬三重項を反映してエントロピーがR
となるように規格化した近藤モデルによって理解でき、近藤温度
,Kは分裂幅
,Kと同程度であり、多チャンネル近藤効果を示しうる二重項
が含まれた擬三重項が重い電子状態と超伝導を担っていることが明らかになった。
野村 拓司*; 山本 裕史*; 吉井 賢資
Journal of the Physical Society of Japan, 89(2), p.024704_1 - 024704_10, 2020/02
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)三角格子上のスピン系の磁性は物性物理の分野で古くから取り扱われている。スピン間に反強磁性的相互作用が存在する場合は、フラストレーションにより複雑な磁気状態が発生すること等から、様々な系の性質が調べられている。本系では、このような系の一つであるNiGaS
の性質を平均場近似により調べた。バンド計算で求まった電子状態を基にしたHatree-Fock法により、中性子回折で観測されているインコメンシュレートなスピン秩序状態を再現することができた。Ni 3d電子間のクーロン相互作用は2eV程度と小さく、Niスピンの値もS=1.1ボーア磁子程度と小さいことから、弱相関系でありNi-Sの共有結合が強いことも判明した。スピン間の相関関数を求めたところ、中性子非弾性散乱の結果と矛盾しない結果も得られた。
目時 直人
Journal of the Physical Society of Japan, 89(2), p.025001_1 - 025001_2, 2020/02
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)重い電子系超伝導体NpPdAl
及び同じ結晶構造を持つ関連物質の
電子状態について、
と
-
結合描像の間に良い対応関係が成り立つことがわかった。これらの物質の希土類及びアクチノイド元素は正方晶の点群
の対称性をもつ強い一軸的な点電荷ポテンシャルの影響を受けている。一連の化合物は
電子数
(
)の増加に伴う
系として考えられ、その電子状態の系統的な変化は
結合描像によってよく表現される。一方、この電子状態の変化は、
系のCePd
Al
の3つの
軌道
,及び
に、
の
電子を
個詰める
-
結合描像によって説明でき、両者の間に物理的な関連が認められる。
中村 翔太*; 兵頭 一志*; 松本 裕司*; 芳賀 芳範; 佐藤 仁*; 上田 茂典*; 三村 功次郎*; 斉木 克祥*; 磯 孝斉*; 山下 穣*; et al.
Journal of the Physical Society of Japan, 89(2), p.024705_1 - 024705_5, 2020/02
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)We have succeeded in growing a new heavy fermion compound YbNiSi
by the flux method. From electrical resistivity, magnetization, specific heat, magnetic torque and X-ray photoemission measurements concluded that this compound is a heavy fermion compound exhibiting an antiferromagnetic order at 0.35 K.
池田 修悟*; 金子 耕士; 田中 佑季*; 川崎 卓郎; 花島 隆泰*; 宗像 孝司*; 中尾 朗子*; 鬼柳 亮嗣; 大原 高志; 望月 健生*; et al.
Journal of the Physical Society of Japan, 89(1), p.014707_1 - 014707_7, 2020/01
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)Magnetism in EuNiIn has been studied by specific heat, magnetic susceptibility, magnetization,
Eu M
ssbauer spectroscopy, and neutron diffraction experiments. The specific heat shows two magnetic transitions at
and
at zero magnetic field. An antiferromagnetic ground state of EuNiIn
has a uniaxial magnetic anisotropy along the b-axis, revealed by the magnetic susceptibility and the M
ssbauer spectroscopy. Single crystal neutron diffraction experiments clarify that this antiferromagnetic structure in the ground state is characterized by the commensurate propagation vector
= (1/2, 1/2, 1/2) which reveals no distinct anomaly at
. The magnetization curve along the b-axis at 2 K shows four successive magnetic field-induced transitions up to 50 kOe and, reaches 7
/f.u. above 190 kOe, The magnetic phase diagram in EuNiIn
has unique characteristics with five magnetic states in low magnetic field.
横田 光史
Journal of the Physical Society of Japan, 89(1), p.014706_1 - 014706_6, 2020/01
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)Magnetic skyrmions are known to exist in ferromagnetic films with dipole-dipole interactions. A two-dimensional Heisenberg ferromagnet with magnetic anisotropy and dipole-dipole interactions is investigated numerically. There exist various topological spin textures. Antiskyrmions coalesce to form spin textures with and
, where
is the topological number. Skyrmion molecules and antiskyrmion molecules as well as donut-shaped spin textures with
appear. The appearance of these (meta)stable topological spin textures depends on the values of temperature and (or) external magnetic field.
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
被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)A high-resolution time-of-flight powder neutron diffraction study of the layered nickel oxide PrSr
NiO
with
and
was performed to characterize the crystal structures of these highly hole-doped nickelates. For the sample with
, the Ni-O bond lengths decrease uniformly with decreasing temperature, and the atomic displacement parameters are similar to those for
. In contrast, for the sample with
, 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
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
sites with different orbital occupancies. The distinct difference between the
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
sites at
in the hole-doped layered nickel oxides.
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, 88(10), p.103701_1 - 103701_5, 2019/10
被引用回数:4 パーセンタイル:25.43(Physics, Multidisciplinary)The electronic structure of the unconventional superconductor was studied by resonant photoelectron spectroscopy (RPES) and angle-resolved photoelectron spectroscopy (ARPES) with soft X-ray synchrotron radiation. The partial
density of states of
were imaged by the
-
RPES and it was found that the
state has an itinerant character, but there exists an incoherent peak due to the strong electron correlation effects. Furthermore, an anomalous admixture of the
states into the
bands was observed at a higher binding energy, which cannot be explained by band structure calculations. On the other hand, the band structure of
was obtained by ARPES and its overall band structure were mostly explained by band structure calculations. These results suggest that the
states of
have itinerant but strongly-correlated nature with enhanced hybridization with the
states.
田端 千紘*; 松村 武*; 中尾 裕則*; 道村 真司*; 垣花 将司*; 稲見 俊哉*; 金子 耕士; 辺土 正人*; 仲間 隆男*; 大貫 惇睦*
Journal of the Physical Society of Japan, 88(9), p.093704_1 - 093704_5, 2019/09
被引用回数:4 パーセンタイル:25.43(Physics, Multidisciplinary)The magnetic order in the magnetic-fild-induced so-called A phase of cubic chiral antiferromagnet EuPtSi was investigated by resonant X-ray scattering (RXS) near the Eu edge. The high flux RXS signal under the magnetic field applied along [111] revealed the first and second order satellite magnetic reflections, indicating that the A phase is a triple-
magnetic ordered state that is described by three propagation vectors lying in the plane normal to the magnetic field direction;
,
, and
. With the high resolution in the reciprocal space achieved in the RXS measurement, it is suggested that the triple-
order strongly couples with the underlying crystal lattice. The triple-
magnetic order is discussed in the context of a magnetic skyrmion lattice on which the geometrical frustration may play a crucial role.
社本 真一
Journal of the Physical Society of Japan, 88(8), p.081008_1 - 081008_11, 2019/08
被引用回数:1 パーセンタイル:65.14(Physics, Multidisciplinary)The local structure study reveals important aspects of the physical properties, because it is closely related to the electronic structure. Some neutron total scattering results are reviewed to show the local functional properties of solids from optical recording to negative thermal expansion to Mott transition materials.