Magnetism in carbon structures

Esquinazi, P.; Höhne, R.

doi:10.1016/j.jmmm.2004.11.154

Cited by 83 publications

(33 citation statements)

References 39 publications

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“…1 This has prompted the study of a variety of defects at different carbon atomic configurations such as graphite, 2 graphene, 3,4 nanotubes, 5,6 and other configurations, 7,8 including defect-free diamond surfaces. 9 Here, in this work, we consider the appearance of localized magnetic moments near defects on the silicon carbide (β-SiC) (110) cubic surface.…”

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Theoretical study of magnetic moments induced by defects at the SiC(110) surface

2011

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The effect of different surface defects on the atomic and electronic structures of cubic β- SiC(110) surface are studied by means of a first-principles calculation based on density-functional theory using the SIESTA code. In the calculations, different spin populations at each atom are allowed. We find that while adsorption of atomic O, N, or H on surface C atoms do not induce magnetic moments on SiC(110), Si vacancies, substitutional C at the Si sites, and H or F adsorbed on Si surface sites induce localized magnetic moments as large as 0.7 μ B at the C atoms close to the defect. The local magnetic moment arrangement varies from ferromagnetic in the case of H adsorption to antiferromagnetic in the Si vacancy and substitutional C cases. The case of H adsorption on Si surface atoms is discussed in detail. It is concluded that magnetism is mainly owing to the local character of the C valence orbitals. Here, in this work, we consider the appearance of localized magnetic moments near defects on the silicon carbide (β-SiC) (110) cubic surface. The quasi-one-dimensional character of the Si-C chains at the surface and the localized character of the carbon atomic valence charge suggest the possibility of defect-induced magnetism. For many years now, silicon carbide has been considered as a compound with important potential practical applications such as power electronics, heterogeneous catalysis support, structural and protective components for use in future nuclear fusion reactors, etc. Recently, this interest has been fostered by the possibility to obtain SiC in different atomic configurations ranging from macromolecules such as fullerenes to two-dimensional sheets and their wrapped configuration in nanotubes (see, for instance, the work of Melinon et al. 10 and references therein).The free SiC(110) surface has been theoretically studied by Sabisch et al. 11 (for a complete review of the different SiC surfaces, see Ref. 12). Unlike other surface orientations, the free SiC(110) surface does not present any reconstruction, as different theoretical works reveal.12 To the best of our knowledge, there is no experimental study published about this surface.Here, we present the results of a first-principles calculation of different defects at the SiC(110) surface. The calculations throughout this work were performed within the densityfunctional theory (DFT), 13 using the generalized gradient approximation (GGA) 14 with partial core corrections. 20 We have found the standard double-ζ basis with polarization orbitals (DZP) satisfactory, and it has been used throughout this work. The bulk calculation yields a lattice constant of 4.41Å (Si-C bond length of 1.91Å), in fair agreement with the experimental value of 4.36Å. We find a partially ionic Si-C bond with a charge transfer of 0.45 electrons to the Si atom as evaluated using a Mulliken population analysis. We obtain a band gap of 1.31 eV, similar to the 1.29 eV band gap calculated by Sabisch et al. 11 and to be compared to the experimental one of 2.417 eV. 21To simulate th...

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Theoretical study of magnetic moments induced by defects at the SiC(110) surface

2011

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“…Recently, ferromagnetism of HOPG (highly oriented pyrolytic graphite) was found at room temperature (Červenka, et al, 2009;Esquinazi & Höhne, 2005;Mombrú et al, 2005). HOPGs often have defects, which form grain boundaries between the polycrystals.…”

Section: Defective Graphenesmentioning

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Electronic States of Graphene-Based Ferromagnets

Hatanaka¹

2011

Graphene Simulation

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“…Recent observation of the occurrence of ferromagnetism in materials purely of carbon origin [85] has created enormous interest in these materials as light nonmetallic magnets would be be very promising for many practical applications if Curie point is well above room temperature.…”

Section: Transitional-metal Free Systemsmentioning

confidence: 99%

Low Dimensional Nanomaterials for Spintronics

Yang

Xiang

2008

One-Dimensional Nanostructures

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Moore's Law in microelectronic technology will break down as the size of individual bits approaches the dimension of atoms; this has been called the end of the silicon road map. For this reason and also for enhancing the multifunctionality of devices, the spin degree of freedom of electron is being investigated for magnetoelectronics applications, i.e., spintronics. Spin-based devices are closely connected with the development of nanotechnology. In this chapter, recent developments of the low-dimensional nanomaterials for spintronics are reviewed. In the first section, the main concepts of spintronics including nanospintronics are briefly discussed. Experimental studies on transition-metal-doped nanowires and nanotubes are summarized in the second section. Extensive theoretical works in this field are reviewed in the third section. Finally, an outlook is given in the last section. SpintronicsSpintronics (a neologism for "spin-based electronics") [1,2], also known as magnetoelectronics, is an emergent technology that exploits the quantum propensity of electrons to spin as well as make use of their charge state. The spin itself is manifested as a detectable weak magnetic energy state characterized as "spin up" and "spin down". Spintronics started attracting massive interest with the discovery of giant magnetoresistance (GMR) in the 1980s, which has already been adopted as the norm in the hard disk drive (HDD) manufacturing industry. Indeed, the impact of spintronics in the HDD industry is a mere indication of things to come.Spintronics has a number of potentially groundbreaking applications that are set to drive next-generation electronics. Although GMR can arguably be considered the driving force for spintronics at present, the biggest potential of spin-based devices is in embedded memories. Magnetoresistive random access memory (MRAM) is expected to revolutionize the memory market and contribute to the development of advanced and versatile computing and personal devices. Advances in instantly 247

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Magnetism in carbon structures

Abstract: We discuss different magnetic phenomena observed in carbon-based structures, in particular the diamagnetism, paramagnetism and ferromagnetism observed in graphite, disordered carbon, fullerenes and irradiated carbon structures.

Cited by 83 publications

References 39 publications

Theoretical study of magnetic moments induced by defects at the SiC(110) surface

Theoretical study of magnetic moments induced by defects at the SiC(110) surface

Electronic States of Graphene-Based Ferromagnets

Low Dimensional Nanomaterials for Spintronics

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