In this work, we report on the modification of electronic and magnetic properties of few layered graphene (FLG) nanoflakes via nitrogen functionalisation carried out using radio frequency (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N2 treatment leads to higher Ndoping levels in the FLGs (4.06 at%) as compared to the ECR process (2.18 at.%), the ferromagnetic behaviour of ECR FLG(118.62 x 10 -4 emu/gm) was significantly higher than the rf-PECVD (0.39 x 10 -4 emu/gm) and pristine graphene (3.47 x 10 -4 emu/gm). While both plasma processes introduce electron donating N-atoms in the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for each FLG type. While, the ECR plasma introduces more sp 2 type nitrogen moieties, the rf-PECVD process led to the formation of sp 3 coordinated nitrogen functionalities, as confirmed through Raman measurements. The samples further characterised using X -ray absorption near edge spectroscopy (XANES) and X-ray, ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Due to the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR functionalised FLGs expressed highest saturation magnetisation behaviour with the lowest field hysteretic features. In comparison, the rf-PECVD samples, displayed the lowest saturation magnetisation owing to the disappearance of magnetic edge states and formation of stable non-radical type defects in the pyrrole type structures. Our experimental results thus provide new evidence to control the magnetic and electronic properties of few layered graphene nanoflakes via control of the plasma-processing route.• INTRODUCTIONIntrinsic magnetism observed in materials without d-or f-electrons has attracted much interest, especially for carbon-based materials and in particular, graphene. There has been a long-standing interest in the development of ferromagnetic graphene for realizing its applications into spintronic devices via the combination of spin and charge. [1][2][3][4] The introduction of magnetic response in graphene via the introduction of edges, vacancy defects or adsorbed atoms has been investigated using both theoretical and experimental means. [1][2][3][4][5][6][7][8][9][10][11][12][13] Various theoretical studies. [3][4][5][6][7][8][9][10] have suggested that zigzag edges or point defects in graphene as the spin units should 3 carry magnetic moment with possible long-range order coupling. This coupling itself can be ferromagnetic or antiferromagnetic, depending on whether the zigzag edges or defects correspond to the same or to different hexagonal sub-lattice of the graphene lattice, respectively. At present, the intrinsic magnetic properties of finite sized graphene sheet are far from being understood, given that the magnetic signal from a finite sized graphene sheet is too weak to be detected by macr...

A comparative study has been made for the defect induced room temperature ferromagnetism of single crystal, poly-crystal, and nanorod zinc oxide (ZnO), based on the magnetic properties and electronic properties by means of X-ray absorption near edge structure spectroscopy (XANES), X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), valence band photoemission spectroscopy (VB-PES), and SQUID-type magnetometry. Magnetic measurement demonstrates the defect-induced ferromagnetic nature at room temperature in different ZnO films and a strong correlation between their electronic properties and magnetic responses. The higher ferromagnetic behaviour in polycrystalline ZnO is attributed to the increasing number of surface defects and native defect sites (oxygen vacancies and zinc interstitials) present in ZnO. XANES studies reveal that the number of unoccupied p states in polycrystalline ZnO is higher than single crystal ZnO as well as nanorod ZnO. The more amount of oxygen vacancy causes the highest intensity the O 1 s peak to appear in the XANES spectra of polycrystalline ZnO. In polycrystalline ZnO, the binding energy of the Zn 2p3/2 core level peak shifted to lower energy that further confirms the increase of the valence band maximum (VBM) position. The VBM of single crystal, poly-crystal, and nanorod-ZnO is 3.64 eV, 3.99 eV, and 3.71 eV, respectively, obtained from UPS (He-I) measurements. VB-PES studies confirm that the number of electrons in the valence band of O 2p - Zn 4sp hybridized states of poly-crystal ZnO is higher than single crystal and nanorod-ZnO.

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