Among several well-known transition metal-based compounds, cleavable van der Waals (vdW) Fe_3-xGeTe₂ (FGT) magnet is a strong candidate for use in two-dimensional (2D) magnetic devices due to its strong perpendicular magnetic anisotropy, sizeable Curie temperature (T_C ~154 K), and versatile magnetic character that is retained in the low-dimensional limit. While the T_C remains far too low for practical applications, there has been a successful push toward improving it via external driving forces such as pressure, irradiation, and doping. Here we present experimental evidence of a room temperature (RT) ferromagnetic phase induced by the electrochemical intercalation of common tetrabutylammonium cations (TBA+) into quasi-2D FGT. We obtained Curie temperatures as high as 350 K with chemical and physical stability of the intercalated compound. The temperature-dependent Raman measurements, in combination with vdW-corrected ab initio calculations, suggest that charge transfer (electron doping) upon intercalation could lead to the observation of RT ferromagnetism. This work demonstrates that molecular intercalation is a viable route in realizing high-temperature vdW magnets in an inexpensive and reliable manner, and has the potential to be extended to bilayer and few-layer vdW magnets.

在几种著名的过渡金属基化合物中，可裂解范德华 (vdW) Fe _3-x GeTe ₂ (FGT) 磁体由于其强大的垂直磁各向异性而成为二维 (2D) 磁性器件的有力候选者、相当大的居里温度（T _C ~154 K）以及在低维极限下保留的多功能磁特性。虽然_TC对于实际应用来说仍然太低，但人们已经成功地通过压力、辐射和掺杂等外部驱动力来改善它。在这里，我们提出了通过将常见的四丁基铵阳离子 (TBA+) 电化学插入准二维 FGT 中诱导室温 (RT) 铁磁相的实验证据。我们获得了高达 350 K 的居里温度，并且插层化合物具有化学和物理稳定性。温度相关的拉曼测量与 vdW 校正的从头计算相结合表明，插层时的电荷转移（电子掺杂）可能导致观察到 RT 铁磁性。这项工作表明，分子嵌入是以廉价且可靠的方式实现高温 vdW 磁体的可行途径，