Electrochemical thinning of Co kagome-lattice layers in ferromagnetic Co3Sn2S2 thin films by bias-induced Co dissolution
Electrochemical thinning of Co kagome-lattice layers in ferromagnetic Co3Sn2S2 thin films by bias-induced Co dissolution
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DOI：
10.1063/5.0134291
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发表时间：
2023-03
影响因子：
3.2
通讯作者：
K. Fujiwara;J. Ikeda;S. Ito;A. Tsukazaki
中科院分区：
文献类型：
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作者：
K. Fujiwara;J. Ikeda;S. Ito;A. Tsukazaki
由功能无机材料和液体电解质组成的固-液界面在外加偏压作用下表现出各种有趣的响应。利用在磁性Weyl半金属Co_3Sn_2S_2薄膜沟道上用离子液体栅电解质制备的双电层器件，我们表明，通过施加负栅电压可以有效地减小导电沟道厚度。在250 K时施加−6 V的栅极电压会导致沟道电阻不可逆地增加。透射电子显微镜显示，结晶的Co 3Sn 2S 2区域的厚度通过施加负偏压而减小，在Co 3Sn 2S 2层的顶部留下Co贫乏的无序区域。这些结果表明，在负偏压的作用下，Co的优先溶解被驱动，这导致在Co 3Sn 2S 2中主要负责导电的Co kagome晶格层断开。与传统的自下而上的薄膜生长方法不同，这种自上而下的厚度控制使我们能够在单个样品中研究Co 3Sn 2S 2的异常输运性质的厚度依赖性。本研究结果将有助于实验验证理论上讨论的磁性Weyl半金属Co_3Sn_2S_2的超薄膜性质。
Solid–liquid interfaces made of functional inorganic materials and liquid electrolytes exhibit various interesting responses by applying an electric bias across the interface. Using an electric-double-layer device fabricated on a thin-film channel of magnetic Weyl semimetal Co3Sn2S2 with an ionic liquid gate electrolyte, we show that the conducting channel thickness can be effectively decreased by applying a negative gate voltage. The application of a gate voltage of −6 V at 250 K gives rise to an irreversible increase in the channel resistance. Transmission electron microscopy reveals that the thickness of the crystallized Co3Sn2S2 region is decreased by applying the negative bias, leaving a Co-poor disordered region on top of the Co3Sn2S2 layer. These results suggest that the preferential dissolution of Co is driven under the application of the negative bias, which leads to the disconnection of Co kagome-lattice layer that is mainly responsible for electrical conduction in Co3Sn2S2. Distinct from conventional bottom-up film growth approaches, this top-down thickness control enables us to examine the thickness dependence of the anomalous transport properties of Co3Sn2S2 in a single sample. The present finding will be useful for experimentally verifying the theoretically discussed ultrathin-film properties of the magnetic Weyl semimetal Co3Sn2S2.