Thickness-Tunable Growth of Composition-Controllable Two-Dimensional Fe<sub><i>x</i></sub>GeTe<sub>2</sub>.

Jiang, Huaning; Zang, Zhihao; Wang, Xingguo; Que, Haifeng; Wang, Lei; Si, Kunpeng; Zhang, Peng; Ye, Yu et al. · Nano Lett · 2022

basic_science · Level V

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Abstract

Two-dimensional (2D) magnetic materials provide an ideal platform for investigating novel magnetism and spin behavior in low-dimensional systems while being restricted by the deficiency of accurate bottom-up synthesis. To overcome this difficulty, a facile and universal flux-assisted growth (FAG) method is proposed to synthesize the multicomponent Fe<sub><i>x</i></sub>GeTe<sub>2</sub> (<i>x</i> = 3-5) with different Fe contents and even alloyed with hetero metal atoms. This one-to-one method ensures the stoichiometry consistency from the Fe<sub><i>x</i></sub>GeTe<sub>2</sub> and M<sub><i>y</i></sub>Fe<sub>5-<i>y</i></sub>GeTe<sub>2</sub> (M = Co, Ni) bulk crystal precursors to the 2D nanosheets, with controllable composition. Tuning the growth temperatures can provide thickness-tunable products. Changeable magnetic properties of Fe<sub><i>x</i></sub>GeTe<sub>2</sub> and alloyed Co<sub><i>y</i></sub>Fe<sub>5-<i>y</i></sub>GeTe<sub>2</sub> are substantiated by the superconducting quantum interference device and reflective magnetic circular dichroism. This method generates thickness-tunable high-crystallinity Fe<sub><i>x</i></sub>GeTe<sub>2</sub> samples without phase separation and exhibits a high tolerance to different substrates and a large temperature window, providing a new avenue to synthesize and explore such multicomponent 2D magnets and even the alloyed ones.