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Chung, J.-H.*; Kwangwoo, S.*; Yokoo, Tetsuya R.; 植田 大地*; 今井 正樹; Kim, H.-S.; Kiem, D. H.; Han, M. J.*; 社本 真一
Scientific Reports (Internet), 15, p.5978_1 - 5978_10, 2025/02
被引用回数:0 パーセンタイル:0.00(Multidisciplinary Sciences)Two dimensional honeycomb ferromagnets host massless Dirac magnons which are a bosonic analogue of Dirac fermions in graphene. The Dirac magnons may become massive and topological when the time-reversal symmetry breaks and an energy gap opens up at the Dirac point, which was experimentally observed in Cr-based van der Waals magnets. Here, we investigate the spin wave excitations in the
magnetic oxide FeTiO
with Fe
electrons (
). Using inelastic neutron scattering, we observe two magnon bands separated by a 1.2-meV gap at the Dirac points indicating that its Dirac magnons are massive. Using the linear spin-wave and density functional theory calculations, we find that the spin-orbit-coupled antisymmetric Dzyaloshinskii-Moriya exchanges can best account for the observed Dirac gap opening. The associated Berry curvature and Chern number (
) indicate that FeTiO
hosts topological spin excitations via time-reversal symmetry breaking of Dirac magnons.
Nabialek, A.*; Chumak, O.*; 関 剛斎*; 高梨 弘毅; Baczewski, L. T.*; Szymczak, H.*
IEEE Transactions on Magnetics, 59(11), p.2501405_1 - 2501405_5, 2023/11
被引用回数:2 パーセンタイル:30.27(Engineering, Electrical & Electronic)The anisotropic magnetoelastic (ME) properties of epitaxial CoFe
Mn
Si(CFMS) Heusler alloy thin films with thicknesses ranging from 8 to 100 nm were investigated using the strain-modulated ferromagnetic resonance (SMFMR) technique. The calculation of the first cubic magnetocrystalline (MC) constant
and the two cubic ME constants
and
was carried out assuming the cubic symmetry of the magnetic layer. A significant negative perpendicular MC anisotropy, of the order of 10
J/m
, was also observed. The investigated parameters were found to be dependent on the thickness of the magnetic layer. The thinnest magnetic layers showed the strongest cubic MC anisotropy and the weakest anisotropy of ME properties. These findings highlight the importance of considering the magnetic layer thickness when evaluating the anisotropy in the ME properties of Heusler alloy thin films.
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
被引用回数:1 パーセンタイル:23.32(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.
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
被引用回数:0 パーセンタイル:0.00(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.
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:0.00(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.
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.
Pospisil, J.; 芳賀 芳範; 神戸 振作; 徳永 陽; 立岩 尚之; 青木 大*; 本多 史憲*; 仲村 愛*; 本間 佳哉*; 山本 悦嗣; et al.
Physical Review B, 95(15), p.155138_1 - 155138_15, 2017/04
被引用回数:15 パーセンタイル:54.36(Materials Science, Multidisciplinary)We investigated the evolution of magnetism in UIrRh
Ge system by systematic study on high-quality single crystals. We find a field-induced first order transition in the vicinity of the critical magnetic field along the
axis in the entire UIr
Rh
Ge system, including the ferromagnetic region.
Yagmur, A.*; 内田 健一*; 井原 和紀*; 井岡 郁夫; 吉川 貴史*; 小野 円佳*; 遠藤 純一*; 柏木 王明*; 中島 哲也*; 桐原 明宏*; et al.
Applied Physics Letters, 109(24), p.243902_1 - 243902_4, 2016/12
被引用回数:3 パーセンタイル:13.48(Physics, Applied)スピンゼーベック効果(SSE)に基づく熱電素子の線抵抗性を調べるため、約3
10
Gyの
線照射試験を実施した。SSE素子には、Pt/Ni
Zn
Fe
O
/GlassとPt/Bi
Y
Fe
O
/Gd
Ga
O
を用いた。SSE素子の熱電特性,磁気特性、構造は、
線照射により影響されないことを確認した。この結果は、SSE素子が厳しい照射環境でさえ熱電素子として適用可能なことを示した。
濱口 由和; 好村 滋洋; 国富 信彦
Journal of the Physical Society of Japan, 17(SUPPL.B-3), p.46 - 48, 1962/00
抄録なし
芳賀 芳範
no journal, ,
UTe is known as an extremely unconventional superconductor. It is also clarified that physical properties both in normal and superconducting states are sample-dependent. Single crystal X-ray diffraction study was performed on UTe
with different quality revealing apparent uranium defects. The resulting difference of physical properties are discussed.
芳賀 芳範; 山本 悦嗣; 松本 裕司*; 白崎 謙次*
no journal, ,
UPt
Al
is known as a uranium intermetallic compound with the hexagonal structure. Detailed crystal structure investigations revealed that uranium atoms form a honeycomb layer stacking along the c-axis. Two magnetic phase transitions were identified by thermodynamic measurements, suggesting a successive change in the magnetic structure.
芳賀 芳範
no journal, ,
Actinides and rare-earths compounds TX
(
= transition metals,
= Ga, In) with the tetragonal HoCoGa
-type structure (so-called 115 compounds) are one of the most extensively studied systems in correlated electron system because of the emergence of intriguing physical properties including heavy fermion superconductivity and various magnetic orderings. In these compounds, 5f electrons are responsible for both magnetic and transport characteristics. In particular, we discuss the emergence of a magnetic ordering in iso-electronic compounds URhGa
and URhIn
.