Decomposition-Induced Room Temperature Magnetism of the Na-intercalated Layered Ferromagnet Fe3-xGeTe2.
Decomposition-Induced Room Temperature Magnetism of the Na-intercalated Layered Ferromagnet Fe3-xGeTe2.
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DOI：
10.1021/acs.nanolett.9b01287
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发表时间：
2019-06
期刊：
影响因子：
10.8
通讯作者：
D. Weber;Amanda H. Trout;D. McComb;J. Goldberger
中科院分区：
文献类型：
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作者：
D. Weber;Amanda H. Trout;D. McComb;J. Goldberger
创造具有室温以上铁磁性的二维货车德瓦耳斯材料是其在基于自旋的应用中的实际利用的基本目标。最近的研究表明，在铁磁体Fe 3-xGeTe 2的剥离薄片中嵌入锂在T ~ 300 K诱导非零磁化。然而，这种实验的纳米级性质排除了插层后结构和化学变化的精确观察。本文报道了钠插层NaFe_（2.78）GeTe_2的制备及其结构和磁性能的研究。钠很容易插入到货车德瓦耳斯间隙中，如通过同步加速器X射线衍射所揭示的。同时，Fe2.78GeTe2层通过化学压力变得重电荷掺杂和应变，但保留其结构和铁磁转变温度约140 K。然而，我们观察到的铁磁非晶铁锗杂质的存在下，在很宽的合成条件，导致室温磁化。这项工作强调了应变和电子控制在操纵2D铁磁体居里温度方面的重要性，同时强调在探索剥落层中的现象时需要进行仔细的化学分析。
The creation of 2D van der Waals materials with ferromagnetism above room temperature is an essential goal towards their practical utilization in spin-based applications. Recent studies suggest that intercalating lithium in exfoliated flakes of the ferromagnet Fe3-xGeTe2 induces a non-zero magnetization at T ~ 300 K. However, the nanoscale nature of such experiments precludes precise observations of structural and chemical changes upon intercalation. Here, we report the preparation of sodium intercalated NaFe2.78GeTe2 as well as investigation into its structure and magnetic properties. Sodium readily intercalates into the van der Waals gap, as revealed by synchrotron X-ray diffraction. Concurrently, the Fe2.78GeTe2 layer becomes heavily charge doped and strained via chemical pressure, yet retains its structure and ferromagnetic transition temperature of ~140 K. However, we observe the presence of a ferromagnetic amorphous iron germanide impurity over a wide range of synthetic conditions, leading to room temperature magnetization. This work highlights the importance of strain and electronic control for manipulating the Curie temperature in 2D ferromagnets, while emphasizing the need for careful chemical analysis when exploring phenomena in exfoliated layers.