We present a detailed analysis of the electronic properties of graphene/Eu/Ni(111). By using angle- and spin-resolved photoemission spectroscopy and ab initio calculations, we show that the intercalation of Eu in the graphene/Ni(111) interface gives rise to a gapped freestanding dispersion of the $\pi {\pi }^{*}$ Dirac cones at the $\overline{\mathrm{K}}$ point with an additional lifting of the spin degeneracy due to the mixing of graphene and Eu states. The interaction with the magnetic substrate results in a large spin-dependent gap in the Dirac cones with a topological nature characterized by a large Berry curvature and a spin-polarized Van Hove singularity, whose closeness to the Fermi level gives rise to a polaronic band.

中文翻译：

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磁性基底上石墨烯中自旋相关的 ππ* 能隙


我们对石墨烯/Eu/Ni(111) 的电子特性进行了详细分析。通过使用角度和自旋分辨光电子能谱以及从头计算，我们表明，Eu 在石墨烯/Ni(111) 界面中的插层会导致 $\pi {\pi }^{*}$ 狄拉克锥体在 $\overline{\mathrm{K}}$ 点由于石墨烯和Eu态的混合而额外提升了自旋简并性。与磁性基底的相互作用导致狄拉克锥中存在较大的自旋相关间隙，其拓扑性质以大贝里曲率和自旋极化范霍夫奇点为特征，其接近费米能级产生极化子带。