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堀内 皓斗*; 荒木 康史; 若林 勇希*; 家田 淳一; 山ノ内 路彦*; 他7名*
Advanced Materials, p.2416091_1 - 2416091_9, 2025/00
被引用回数：0 パーセンタイル：0.00(Chemistry, Multidisciplinary)Spin Berry curvature characterizes the band topology as the spin counterpart of Berry curvature and is crucial in generating novel spintronics functionalities. By breaking the crystalline inversion symmetry, the spin Berry curvature is expected to be significantly enhanced; this enhancement will increase the intrinsic spin Hall effect in ferromagnetic materials and, thus, the spin-orbit torques (SOTs). However, this intriguing approach is not applied to devices; generally, the spin Hall effect in ferromagnet/heavy-metal bilayer is used for SOT magnetization switching. Here, SOT-induced partial magnetization switching is demonstrated in a single layer of a single-crystalline Weyl oxide SrRuO
(SRO) with a small current density of 
. Detailed analysis of the crystal structure in the seemingly perfect periodic lattice of the SRO film reveals barely discernible oxygen octahedral rotations with angles of 
near the interface with a substrate. Tight-binding calculations indicate that a large spin Hall conductivity is induced around small gaps generated at band crossings by the synergy of inherent spin-orbit coupling and band inversion due to the rotations, causing magnetization reversal. The results indicate that a minute atomic displacement in single-crystal films can induce strong intrinsic SOTs that are useful for spin-orbitronics devices.
丸山 忠司; 小野瀬 庄二; 皆藤 威二; 堀内 博人
Journal of Nuclear Science and Technology, 34(10), p.1006 - 1014, 1997/10
ホットプレス炭化ホウ素(B4C)ペレットを、高速実験炉「常陽」で燃焼度170E+26CAP/M3,フルエンス2E+26N/M2(E
0.1MEV)、最高温度1200
までの条件で照射した。照射後試験では、微細組織変化、ヘリウム放出、スエリングおよび熱伝導度を測定した。高燃焼度まで照射したB4Cペレットは激しく割れ、ペレットからのヘリウム放出は、最初は低い値を示すが80E+26CAP/M3の燃焼度を超えるとペレットの著しい割れのためにヘリウム放出が促進された。スエリングは燃焼度とともに増加し、80E+26CAP/M3の燃焼度までは100E+26CAP/M3あたり約3.5%のスエリング速度であったが、それ以上の燃焼度になると、ヘリウム放出の増大に対応してスエリングは減少傾向を示した。スエリングとヘリウム放出の相関について解析し、B4Cペレットのスエリングはペレット内に蓄積するヘリウム保持量で表すことが出来ることを示した。B4Cの熱伝
single layer with a spontaneous oxygen atomic displacement堀内 皓斗*; 若林 勇希*; 荒木 康史; 家田 淳一; 山ノ内 路彦*; 他6名*
no journal, ,
Perovskite oxide SrRuO (SRO), which is also known as a ferromagnetic Weyl semimetal, is promising for realizing efficient spin-orbitronics devices. Here, we demonstrated an SOT-induced magnetization switching in a single-phased ferromagnetic SRO single layer. An important finding is that 7.5 
10% of the magnetization in the 26 nm-thick SRO film was stably switched by the in-plane-current application. To clarify the reason for the obtained SOT in our SRO single layer, where spatial inversion symmetry seemingly is maintained, we closely analyzed the crystal structure using annular bright-field scanning transmission electron microscopy (ABF-STEM). We found that oxygen octahedral rotation (5 degrees) occurs especially near the interface between SRO and STO. By comparing the results with our theoretical calculation based on the tight-binding model, the observed partial single-layer magnetization switching can be attributed to the octahedral rotation and the associated large intrinsic spin Hall effect near the interface. We obtained a small switching current density of 3.1 5.3 MA cm
, one order of magnitude smaller than conventional SOT systems consisting of a ferromagnet/heavy metal bilayer. This result implies that only a tiny spontaneous displacement of atoms in perovskite oxides plays a pivotal role in spin-orbitronics device applications.
