Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
太田 玖吾*; 松本 裕司*; 渡部 悠貴*; 金子 耕士; 田端 千紘; 芳賀 芳範
New Physics; Sae Mulli, 73(12), p.1170 - 1173, 2023/12
ハニカム格子を持つ反強磁性体UPt
Al
の磁気構造を決定するために中性子散乱実験を行った。U
Pt
Al
は
=9Kと
=26Kで二つの相転移を示す。
の第一相では、
=(1/3, 0, 0)の伝搬ベクトルで記述される磁気反射が観測された。
のフェーズIIでは、
=(1/3, 0, 0)と
=(1/2, 0, 0)の磁気反射が観測され、
=(1/3, 0, 0)の磁気反射強度は弱いが有限であった。温度依存強度のヒステリシスは
での相転移にまたがって観測され、
での転移が1次転移であることを示唆している。
太田 玖吾*; 渡部 悠貴*; 芳賀 芳範; Iesari, F.*; 岡島 敏浩*; 松本 裕司*
Symmetry (Internet), 15(8), p.1488_1 - 1488_13, 2023/07
被引用回数:1 パーセンタイル:55.90(Multidisciplinary Sciences)Polycrystalline and single crystalline CePt
Al
samples were synthesized and characterized using EPMA, XRD, XAS and magnetization measurements. The valence of Ce in this compound is trivalent, in agreement with magnetic susceptibility and XAS spectra. The analysis of EXAFS spectra indicates the formation of a honeycomb lattice rather than the disordered hexagonal structure.
松本 裕司*; 芳賀 芳範; 山本 悦嗣; 竹内 徹也*; 三宅 厚志*; 徳永 将史*
Journal of the Physical Society of Japan, 90(7), p.074707_1 - 074707_6, 2021/07
被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)A uranium intermetallic compound UPt
Ga
was successfully synthesized. This compound crystallizes in the hexagonal Sc
Fe
Si
-type structure. Antiferromagnetic transition with highly magnetic anisotropy was established by the physical property measurements.
酒井 宏典; 松本 裕司*; 芳賀 芳範; 徳永 陽; 神戸 振作
Physical Review B, 103(8), p.085114_1 - 085114_8, 2021/02
被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)重い電子系反強磁性体CeRhSi
において、
Si核核磁気共鳴(NMR)を用いて、圧力下相図について微視的に調べた。NMRデータから、反強磁性伝搬ベクトル
に依らない単一サイト近藤効果の特徴的温度スケール
を導出した。圧力下の反強磁性臨界点において
の発散的異常は見られず、重い電子系の典型的なDoniach描像と矛盾しない結果が得られた。
芳賀 芳範; 菅井 孝志*; 松本 裕司*; 山本 悦嗣
JPS Conference Proceedings (Internet), 29, p.013003_1 - 013003_5, 2020/02
Crystal structure and magnetic property of UPt
Al
is investigated. A single crystal X-ray diffraction experiment identified the hexagonal unit cell with a disordered structure in the uranium containing layer. A series of superstructure reflections were found. They are successfully indexed as (
/3
/3 0), however, with a streak along the
direction. A layered structure model containing honeycomb arrangement of uranium atoms is proposed. Preliminary magnetization measurements on a polycrystalline sample are also presented.
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:2 パーセンタイル:21.38(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.
松本 裕司*; 芳賀 芳範; 立岩 尚之; 山本 悦嗣; Fisk, Z.*
Journal of the Physical Society of Japan, 87(2), p.024706_1 - 024706_4, 2018/02
被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)Single crystal samples of UPtIn with the hexagonal structure are grown from indium flux. Strong uniaxial magnetic anisotropy is revealed from magnetic property measurements. Specific heat measurement reveals a significant deviation from -linear behavior, indicating the smaller electronic specific heat than the previous study.
藤森 伸一; 小畠 雅明; 竹田 幸治; 岡根 哲夫; 斎藤 祐児; 藤森 淳; 山上 浩志; 松本 裕司*; 山本 悦嗣; 立岩 尚之; et al.
Physical Review B, 96(12), p.125117_1 - 125117_9, 2017/09
被引用回数:10 パーセンタイル:45.30(Materials Science, Multidisciplinary)The Fermi surface and band structure of have been studied by angle resolved photoelectron spectroscopy (ARPES) with the incident photon energies of
= 665-735 eV. Detailed band structure and the three-dimensional shape of the Fermi surface were derived experimentally, and they are quantitatively explained by the band-structure calculation based on the density functional approximation. Comparison of the experimental ARPES spectra of
with those of
shows that they have considerably different spectral profiles particularly in the energy range of
- 1 eV. Some energy bands with their energy dispersions of about 1 eV observed in
are missing in the ARPES spectra of
measured along the same high symmetry line of Brillouin zone, suggesting that U 5
states form these bands in
. The relationship between the ARPES spectra of
and
is very different from the case between
and
where their intrinsic difference is limited only in the very vicinity of the Fermi energy. The present result argues that the U 5
electrons in
have strong hybridization with ligand states, and essentially have an itinerant character.
芳賀 芳範; 松本 裕司*; Pospisil, J.; 立岩 尚之; 山本 悦嗣; 山村 朝雄*; Fisk, Z.*
Journal of Physics; Conference Series, 807(1), p.012015_1 - 012015_4, 2017/04
被引用回数:1 パーセンタイル:33.96(Physics, Condensed Matter)Transport characteristics of an antiferromagnetic uranium compound URhIn are studied. The antiferromagnetic transition leads to a formation of a gap on the Fermi surface as demonstrated by a hump in the resistivity behavior as a function of temperature. Hall effect, magnetoresistance and de Haas-van Alphen study consistently demonstrate a small carrier concentration in the antiferromagnetic state suggesting that majority of the Fermi surface vanishes.
松本 裕司*; 芳賀 芳範; 立岩 尚之; 青木 晴善*; 木村 憲彰*; 山村 朝雄*; 山本 悦嗣; 松田 達磨*; Fisk, Z.*; 山上 浩志*
Journal of the Physical Society of Japan, 85(10), p.104709_1 - 104709_7, 2016/10
被引用回数:2 パーセンタイル:20.02(Physics, Multidisciplinary)dHvA oscillations were detected on an actinide compound ThRuSi
which is regarded as a reference to strongly correlated electron systems URu
Si
and CeRu
Si
. Observed Fermi surfaces well coincides with the band structure calculations, as well as experimentally obtained ones for a heavy fermion compound CeRu
Si
. On the other hand, Fermi surfaces of URu
Si
have significantly different characteristics, suggesting an itinerant ground state of 5f electrons.
江見 直哉*; 濱端 良輔*; 中山 大将*; 三木 俊宙*; 小山 岳秀*; 上田 光一*; 水戸 毅*; 小堀 洋*; 松本 裕司*; 芳賀 芳範; et al.
Journal of the Physical Society of Japan, 84(6), p.063702_1 - 063702_4, 2015/06
被引用回数:10 パーセンタイル:58.15(Physics, Multidisciplinary)NMR/NQR measurements have been carried out on ThRuSi
and LaRu
Si
which are the nonmagnetic references of the heavy fermion URu
Si
. Ru-NQR measurements suggest the relatively close electronic configuration between ThRu
Si
and URu
Si
at high temperature. However, significant delocalization was observed in URu
Si
at low temperatures. Si-NMR experiments on URu
Si
revealed Ising-like spin fluctuations in the hidden-order state.
芳賀 芳範; 松本 裕司*; 立岩 尚之; 山本 悦嗣; 木村 憲彰*; 山村 朝雄*; Fisk, Z.
Journal of Physics; Conference Series, 592(1), p.012036_1 - 012036_5, 2015/03
被引用回数:2 パーセンタイル:60.63(Physics, Atomic, Molecular & Chemical)We investigate the modification of the electronic state of ThRuSi
upon replacing non magnetic Th by U. We successfully observed the quantum oscillation signals from the Fermi surface. The observed Fermi surfaces did not show a significant change in size for the U
Th
Ru
Si
sample. However the enhancement of the cyclotron effective mass demonstrates the hybridization of the 5
states with the conduction bands.
松本 裕司*; 芳賀 芳範; 立岩 尚之; 青木 晴善*; 木村 憲彰*; 松田 達磨*; 山本 悦嗣; Fisk, Z.; 山上 浩志*
JPS Conference Proceedings (Internet), 3, p.011096_1 - 011096_5, 2014/06
Electronic differences between heavy Fermion CeRuSi
and isoelectronic nonmagnetic ThRu
Si
have been investigated. We succeeded in observing the de Haas-van Alphen oscillation in a high quality single crystal of ThRu
Si
. The mean free path of conduction carriers has been estimated as 6400
, indicating the high quality of the present sample.
松本 裕司; 芳賀 芳範; 立岩 尚之; 山本 悦嗣; 木村 憲彰*; 青木 晴善*; Fisk, Z.
JPS Conference Proceedings (Internet), 3, p.011097_1 - 011097_5, 2014/06
Single crystal samples of a new uranium compound URhIn with the well-known tetragonal HoCoGa
-type structure have been grown by the indium flux method. Although this compound is isostructural to a Ga-analogue URhGa
, the unit cell volume is significantly larger in URhIn
. In contrast to non-magnetic behavior in the isostructural URhGa
, URhIn
has a magnetic ground state with a magnetic transition at 98 K, indicating a drastic difference in electronic states between these compounds.
松本 裕司; 松田 達磨; 立岩 尚之; 山本 悦嗣; 芳賀 芳範; Fisk, Z.
Journal of the Korean Physical Society, 63(3), p.363 - 366, 2013/08
被引用回数:8 パーセンタイル:50.51(Physics, Multidisciplinary)We have studied single crystal growth and physical properties of the UTAl
system. We have successfully grown UT
Al
(T = Cr, Ti, W and Mo) using Al self flux and characterized the crystals using electron probe microanalyzer (EPAM) and X-ray diffraction, and measured their magnetic and electric properties. The ground states of UT
Al
(T = Cr, Mo and W) are Pauli paramagnetic as is likely also in UTi
Al
. The effective masses of UCr
Al
and UTi
Al
are only weakly enhanced.
酒井 宏典; 徳永 陽; 神戸 振作; 松本 裕司; 松田 達磨; 芳賀 芳範
Journal of the Korean Physical Society, 63(3), p.352 - 355, 2013/08
被引用回数:4 パーセンタイル:33.49(Physics, Multidisciplinary)正方晶ThCrSi
型結晶構造を持つ反強磁性体CeRh
Si
のNMR研究を単結晶を用いて行った。磁化率と同じく、ナイトシフトは
軸方向にイジング型磁気異方性を示した。
Si核の超微細結合定数を
軸方向、
軸方向に対して、ナイトシフトと磁化率のプロットから決定した。
酒井 宏典; 神戸 振作; 徳永 陽; 松本 裕司; 立岩 尚之; 芳賀 芳範; Fisk, Z.
Physical Review B, 88(4), p.045123_1 - 045123_8, 2013/07
被引用回数:5 パーセンタイル:25.07(Materials Science, Multidisciplinary)=98Kの反強磁性体URhIn
について、核磁気共鳴(NMR/NQR)法を用いて研究を行った。常磁性状態におけるNQRスペクトルから、結晶学的に異なるIn(1)サイトとIn(2)サイトにおける電場勾配を決定し、反強磁性秩序状態におけるNMRスペクトルから、整合反強磁性秩序が起きていることがわかった。内場はIn(2)サイトで約21kOe、In(1)サイトではキャンセルしていることもわかった。核磁気緩和率
測定から、In(1)サイトでは、150K以下においてコリンハ則が見られ、In(2)サイトでは、臨界発散に伴う
の増大が見られた。これらの実験事実から、反強磁性構造について議論した。
松本 裕司*; 芳賀 芳範; 立岩 尚之; 酒井 宏典; 松田 達磨; 山本 悦嗣; Fisk, Z.
Physical Review B, 88(4), p.045120_1 - 045120_6, 2013/07
被引用回数:7 パーセンタイル:33.13(Materials Science, Multidisciplinary)We have grown the new uranium compound URhIn with the tetragonal HoCoGa
-type by the In self flux method. In contrast to the nonmagnetic ground state of the isoelectronic analogue URhGa
, URhIn
is an antiferromagnet with antiferromagnetic transition temperature
= 98 K. The moderately large electronic specific heat coefficient
= 50 mJ/K
mol demonstrates the contribution of 5f electrons to the conduction band.
松本 裕司; 木村 憲彰*; 小松原 武美*; 青木 晴善*; 栗田 伸之*; 寺嶋 太一*; 宇治 進也*
Journal of Physics; Conference Series, 391, p.012042_1 - 012042_4, 2012/12
被引用回数:1 パーセンタイル:43.46(Physics, Multidisciplinary)CeRuSi
は、
of 350mJ/mol K
を持つ典型的な重い電子系物質である。この物質の[001]方向に磁場を印加したときに、7.7Tでメタ磁性転移を引き起こす。一方、この(001)面内に磁場を印加したときは、メタ磁性を引き起こさない。この大きな磁気異方性は、CeをLaに置換したときにおいても、常に残っている。CeをLaに置換すると、
=0.91で反強磁性秩序を起こし、Ceが希薄濃度になると反強磁性秩序は消失する。そして、Ce濃度が非常に薄い濃度領域で不純物近藤効果を引き起こす。
=0.02の試料では、近藤温度を1.3Kと見積もった。その濃度において、dHvA振動の観測に成功した。そして、温度に対してフェルミ面が連続的に変化していることを明らかにした。このことは、f電子は、不純物近藤効果を起こし近藤シングレットを形成したときは遍歴していて、温度の上昇とともに局在化していくことを示している。
岡根 哲夫; 竹田 幸治; 山上 浩志; 藤森 淳; 松本 裕司; 木村 憲彰*; 小松原 武美*; 青木 晴善*
Physical Review B, 86(12), p.125138_1 - 125138_11, 2012/09
被引用回数:12 パーセンタイル:46.36(Materials Science, Multidisciplinary)X-ray absorption (XAS) and its magnetic circular dichroism (XMCD) were measured at the Ce absorption edges of ferromagnetic CeRu
Ge
and paramagnetic CeRu
Si
: both compounds are considered to be located near the boundary of delocalization of Ce 4
electrons. While the XAS line shape varies clearly reflecting the variation in the 4
delocalization, the line-shape variation in XMCD is hardly discernible under various conditions of temperature and magnetic field. The XAS line-shape variation can be explained as effects of the variations in the 4
occupation number and in the ratio of
= 7/2 states in the ground states, both of which are closely related to the 4
delocalization. The 4
delocalization also causes a decrease in the ratio of the orbital magnetic moment to the spin magnetic moment. The magnetic-field dependence of XAS suggests that the Ce 4
electrons retain a delocalized character across the metamagnetic transition in CeRu
Si
.