Embedding atomic cobalt into graphene lattices to activate room-temperature ferromagnetism

Wei Hu,Hengli Duan,Na Li,Ying Lu,Zhihu Sun,Yao Wang,Chao Wang,Qianqian Ji,Hao Tan,Wensheng Yan,Fengchun Hu,Guinan Li

doi:10.1038/s41467-021-22122-2

Abstract

Graphene is extremely promising for next-generation spintronics applications; however, realizing graphene-based room-temperature magnets remains a great challenge. Here, we demonstrate that robust room-temperature ferromagnetism with TC up to ∼400 K and saturation magnetization of 0.11 emu g−1 (300 K) can be achieved in graphene by embedding isolated Co atoms with the aid of coordinated N atoms. Extensive structural characterizations show that square-planar Co-N4 moieties were formed in the graphene lattices, where atomically dispersed Co atoms provide local magnetic moments. Detailed electronic structure calculations reveal that the hybridization between the d electrons of Co atoms and delocalized pz electrons of N/C atoms enhances the conduction-electron mediated long-range magnetic coupling. This work provides an effective means to induce room-temperature ferromagnetism in graphene and may open possibilities for developing graphene-based spintronics devices.

Highlights

Graphene is extremely promising for next-generation spintronics applications; realizing graphene-based room-temperature magnets remains a great challenge
Co K-edge Xray absorption near edge structure (XANES) spectra (Fig. 1f and Supplementary Fig. 3), Fourier-transformed (FT) k3-weighted Co K-edge extended X-ray absorption fine structure (EXAFS) spectra (Fig. 1g), and wavelet transform (WT) analysis (Fig. 1h) show that Co exists as isolated atoms in graphene
In summary, we have explored the possibility of achieving stable room-temperature ferromagnetic ordering in graphene by embedding single magnetic transition metal (TM) atoms in the lattice via the strong chemical bonds in the TM-Nx moieties

Summary

Introduction

Graphene is extremely promising for next-generation spintronics applications; realizing graphene-based room-temperature magnets remains a great challenge. Motivated by the above consideration, we propose a coordination atom assisted strategy by embedding magnetic TM into graphene lattices under the assistance of coordinated N atoms, where stable room-temperature ferromagnetism can be achieved in graphene This strategy is exemplified by the singlemetal-atomic Co-N4 moiety doped graphene, which was synthesized via an impregnation-pyrolysis method, and exhibits unprecedented ferromagnetic orderings with Curie temperature (TC) up to ∼400 K. The Co-N4 doped graphene possesses unique electronic structure where only one spin channel crosses the Fermi level, which is beneficial for the generation of spin-polarized current in spintronics[31] This deliberately designed strategy opens up an avenue for the development of graphene-based spintronic devices

Methods

Results

Conclusion