Tuning the Curie temperature of a two-dimensional magnet/topological insulator heterostructure to above room temperature by epitaxial growth
Tuning the Curie temperature of a two-dimensional magnet/topological insulator heterostructure to above room temperature by epitaxial growth
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DOI：
10.1103/physrevmaterials.7.104004
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发表时间：
2023-08
影响因子：
3.4
通讯作者：
Wenyi Zhou;A. Bishop;Xiyue S. Zhang;K. Robinson;I. Lyalin;Ziling Li;Ryan Bailey-Crandell;
中科院分区：
文献类型：
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作者：
Wenyi Zhou;A. Bishop;Xiyue S. Zhang;K. Robinson;I. Lyalin;Ziling Li;Ryan Bailey-Crandell;
二维（2D）货车德瓦耳斯（vdW）磁体和拓扑绝缘体（TI）的异质结构作为高效自旋扭矩开关、量子反常霍尔效应和手征自旋织构的候选材料而受到极大关注。然而，由于许多vdW磁体的居里温度低于室温，我们想了解如何修改材料以使其磁有序稳定到更高的温度。在这项工作中，我们利用分子束外延系统地调整居里温度（$T_C$）在薄膜Fe $_3$GeTe$_2 $/Bi $_2$Te$_3 $从块状值（$\sim$220 K）到室温以上，通过增加生长温度从300 $^\circ$C到375 $^\circ$C。对于在375 $^\circ$C下生长的样品，横截面扫描透射电子显微镜（STEM）揭示了不同的Fe $_m $Ge $_n $Te $_2 $组合物（例如Fe $_5 $Ge $_2 $Te $_2 $和Fe $_7 $Ge $_6 $Te $_2 $）的自发形成以及在vdW间隙中的插层，这是增强的居里温度的可能来源。这一发现为开发各种具有新特性的Fe_mGe_nTe_2/TI异质结材料铺平了道路。
Heterostructures of two-dimensional (2D) van der Waals (vdW) magnets and topological insulators (TI) are of substantial interest as candidate materials for efficient spin-torque switching, quantum anomalous Hall effect, and chiral spin textures. However, since many of the vdW magnets have Curie temperatures below room temperature, we want to understand how materials can be modified to stabilize their magnetic ordering to higher temperatures. In this work, we utilize molecular beam epitaxy to systematically tune the Curie temperature ($T_C$) in thin film Fe$_3$GeTe$_2$/Bi$_2$Te$_3$ from bulk-like values ($\sim$220 K) to above room temperature by increasing the growth temperature from 300 $^\circ$C to 375 $^\circ$C. For samples grown at 375 $^\circ$C, cross-sectional scanning transmission electron microscopy (STEM) reveals the spontaneous formation of different Fe$_m$Ge$_n$Te$_2$ compositions (e.g. Fe$_5$Ge$_2$Te$_2$ and Fe$_7$Ge$_6$Te$_2$) as well as intercalation in the vdW gaps, which are possible origins of the enhanced Curie temperature. This observation paves the way for developing various Fe$_m$Ge$_n$Te$_2$/TI heterostructures with novel properties.