Enhancement of permittivity off-diagonal terms in rare earth transition metal / heavy metal hetero-structured films
Enhancement of permittivity off-diagonal terms in rare earth transition metal / heavy metal hetero-structured films
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DOI：
10.3389/fphy.2022.949571
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Kei Matsumoto;P. V. Thach;S. Sumi;S. Ranjbar;K. Tanabe;H. Awano;Shihao Wang;T. Ishibashi
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文献类型：
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作者：
Kei Matsumoto;P. V. Thach;S. Sumi;S. Ranjbar;K. Tanabe;H. Awano;Shihao Wang;T. Ishibashi
自旋霍尔效应、Dzyaloshinskii-Moriya相互作用、Rashba效应等对自旋电子导电现象的发展起着非常重要的作用，这是由于由铂和钨等重金属组成的异质界面的空间反转对称性被打破，这是由于SOI(自旋轨道相互作用)造成的。这些研究大多是在GHz以下的频域进行的，在光的能量领域进行的研究很少。因此，在光能范围内，测量了Pt界面上SOI较大的TbCo/Pt异质结构薄膜和Cu界面上SOI较小的TbCo/Cu异质结构薄膜的磁光克尔效应谱，并分别研究了它们的介电常数张量。结果表明，在TbCo/Pt异质结薄膜中，在小于2.5 eV的能区，TbCo薄层的非对角分量实部的介电常数比块体TbCo的介电常数增加了一倍左右。然而，在TbCo/Cu异质结构薄膜中没有观察到这种增加。这一结果表明，即使在光能区，也可能出现破坏空间反转对称性的铂异质界面的影响。此外，还证实了使用具有较大SOI的W的TbCo/W异质结构薄膜具有与TbCo/Pt相同的增长效应。
The spin Hall effect, Dzyaloshinskii-Moriya interaction, Rashba effect, etc. are extremely important effects for the development of the conduction phenomenon of spin electronics due to the breaking of the spatial inversion symmetry of the hetero interface made of heavy metals such as Pt and W. These are due to SOI (spin-orbit interaction). Most of these studies have been conducted in the frequency domain below GHz, and there are few studies in the energy domain of light. Therefore, in the region of light energy, the magnetic optical Kerr effect spectra of the TbCo/Pt hetero-structured film with large SOI from the Pt interface and the TbCo/Cu hetero-structured film with small SOI from the Cu interface were measured, and the permittivity tensors were investigated respectively. As a result, in the TbCo/Pt hetero-structured film, the dielectric constant off-diagonal component real part of the thin TbCo layer increased about twice as much as that of bulk TbCo in the energy region smaller than 2.5 eV. However, this increase was not observed in the TbCo/Cu hetero-structured film. This result suggests that the influence of the Pt hetero interface where the spatial inversion symmetry is broken may appear even in the energy region of light. Furthermore, it has been confirmed that TbCo/W hetero-structured film using W with a large SOI has the same increasing effect as that of the TbCo/Pt.