轨道键和局部磁性在 Fe3GeTe2 和 Fe4GeTe2 中的作用：对超薄纳米器件的影响,ACS Applied Nano Materials

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轨道键和局部磁性在 Fe3GeTe2 和 Fe4GeTe2 中的作用：对超薄纳米器件的影响
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2022-07-23 , DOI: 10.1021/acsanm.2c01576
Seong-Rae Kim _{1,

2} , In Kee Park ₃ , Jong-Gyu Yoo _{1,

2} , Junho Seo _{2,

4} , Jeong-Gyu Kim _{1,

2} , Jae-Hoon Park _{1,

2} , Jun Sung Kim _{2,

4} , Kyoo Kim ₅ , Geunsik Lee ₃ , Kyung-Tae Ko ₆

Affiliation

我们研究了键合环境和库仑屏蔽在范德华 (vdW) 金属铁磁体 Fe ₃ GeTe ₂ (FGT3) 和 Fe ₄ GeTe ₂ (FGT4) 中的作用。使用 X 射线吸收光谱 (XAS) 和从头算计算检查了 FGT3 和 FGT4 的对比磁各向异性的电子起源。我们发现FGT4的轨道磁矩（0.050 μ _B /Fe）小于FGT3的轨道磁矩（0.11 μ _B /Fe）。在这里，Fe 哑铃结构的差异导致 FGT3(FGT4) 中更多（更少）局部化的 d _{3 z ² - r ²}态，以及 t 的有效轨道能级分裂_2g流形导致 FGT3 中的大磁晶各向异性。XAS 测量和计算还表明，在 FGT4 中比在 FGT3 中更有效地筛选库仑相互作用。以下理论分析表明，屏蔽库仑相互作用成为确定磁各向异性能量的关键参数，特别是在厚度依赖性方面。最后，我们讨论了最近的实验演示可以根据键合环境的影响来理解。我们的研究揭示了控制用于超薄纳米器件的 vdW 铁磁体磁性的基本电子自由度。

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Role Of Orbital Bond and Local Magnetism In Fe3GeTe2 and Fe4GeTe2: Implication For Ultrathin Nano Devices

We investigated the role of the bonding environment and Coulomb screening in the van der Waals (vdW) metallic ferromagnets Fe₃GeTe₂ (FGT3) and Fe₄GeTe₂ (FGT4). The electronic origins of the contrasting magnetic anisotropy of FGT3 and FGT4 were examined using X-ray absorption spectroscopy (XAS) and ab initio calculations. We found that the orbital magnetic moment of FGT4 (0.050 μ_B/Fe) is smaller than that of FGT3 (0.11 μ_B/Fe). Here, the difference in Fe dumbbell structure gives rise to the more (less) localized d_3z²–r² states in FGT3(FGT4), and an effective orbital level splitting of t_2g manifolds results in the large magnetocrystalline anisotropy in FGT3. The XAS measurements and the calculations additionally show that the Coulomb interaction is more effectively screened in FGT4 than in FGT3. The following theoretical analyses show that the screened Coulomb interaction becomes a key parameter to determine the magnetic anisotropy energy, especially in the thickness dependence. Finally, we discuss that the recent experimental demonstrations can be understood upon the effect of the bonding environment. Our investigation reveals essential electronic degrees of freedom to control the magnetism of the vdW ferromagnet for ultrathin nano devices.

更新日期：2022-07-23

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