论文标题
拓扑绝缘子的二维铁磁扩展
Two-dimensional ferromagnetic extension of a topological insulator
论文作者
论文摘要
在3D拓扑绝缘子（Ti）中诱导拓扑表面状态（TSS）的狄拉克点的磁性间隙是无需耗散电荷和自旋电流的途径。理想情况下，磁顺序仅存在于表面，而不存在于大体中，例如通过铁磁（FM）层的接近度。但是，尚未观察到这种接近性诱导的狄拉克质量差距，这可能是由于TSS的重叠不足和FM子系统。在这里，我们采用了另一种方法，即FM扩展，使用3D ti bi $ _2 $ te $ _3 $的薄膜，与Lattice匹配的Van der Waals Ferromagnet Mnbi Mnbi $ _2 $ _2 $ _4 $ _4 $ _4 $相连。 X射线磁性二分色和电气传输测量结果证明了具有平面外各向异性和$ \文本{t} _ \ text {c} \ of text {c} \大约15 k的稳健2D铁磁学和临界温度的临界温度。使用角度分辨的光电子光谱，我们观察到在2D FM相中显着的磁性间隙，而表面在T $ _C $上方的顺磁性相中保持无间隙。这个巨大的间隙表明将TSS搬迁至表面附近的FM有序的MN矩，从而导致较大的相互重叠。
Inducing a magnetic gap at the Dirac point of the topological surface state (TSS) in a 3D topological insulator (TI) is a route to dissipationless charge and spin currents. Ideally, magnetic order is present only at the surface and not in the bulk, e.g. through proximity of a ferromagnetic (FM) layer. However, such a proximity-induced Dirac mass gap has not been observed, likely due to insufficient overlap of TSS and the FM subsystem. Here, we take a different approach, namely FM extension, using a thin film of the 3D TI Bi$_2$Te$_3$, interfaced with a monolayer of the lattice-matched van der Waals ferromagnet MnBi$_2$Te$_4$. Robust 2D ferromagnetism with out-of-plane anisotropy and a critical temperature of $\text{T}_\text{c}\approx$~15 K is demonstrated by X-ray magnetic dichroism and electrical transport measurements. Using angle-resolved photoelectron spectroscopy, we observe the opening of a sizable magnetic gap in the 2D FM phase, while the surface remains gapless in the paramagnetic phase above T$_c$. This sizable gap indicates a relocation of the TSS to the FM ordered Mn moments near the surface, which leads to a large mutual overlap.
