Supercritical CO2‐induced New Chemical Bond of C−O−Si in Graphdiyne to Achieve Robust Room‐Temperature Ferromagnetism

Room-temperature ferromagnetism is successfully achieved in graphdiyne by supercritical CO₂ treatment. Structural defects induced by supercritical CO₂ in graphdiyne provides local magnetic moments that lead to ferromagnetism. Furthermore, the formation of new C−O−Si bond helps to enhance charge transfer and generate long-range ferromagnetic order.

Abstract

The realization of ferromagnetic ordering of two-dimensional (2D) carbon material graphdiyne (GDY) has attracted great attention due to its promising application in spin semiconductor devices. However, the absence of localized spins makes the pristine GDY intrinsically nonferromagnetic. Herein, we report the realization of robust room-temperature (RT) ferromagnetism (FM) with Curie temperature (T_C ) up to 325 K for GDY Nanosheets (GDYNs) by supercritical CO₂ (SC CO₂). Experimental and theoretical calculations reveal that the new chemical bond of C−O−Si can be formed because of the unique effect of SC CO₂, which help to enhance the charge transfer and generates long-range ferromagnetic order. The RT saturation magnetization (M_S ) reaches 1.125 emu/g, which is much higher than that of carbon-based materials reported up to now. Meanwhile, by changing the conditions of SC CO₂ such as pressure, ferromagnetic responses can be manipulated, which is great for potential spintronics applications of GDY.

Zum Volltext