Magnetic order in graphite: Experimental evidence, intrinsic and extrinsic difficulties

Esquinazi, P.; Barzola‐Quiquia, J.; Spemann, D.; Rothermel, Martin; Ohldag, Hendrik; Garcı́a, N.; Setzer, A.; Butz, T.

doi:10.1016/j.jmmm.2009.06.038

Cited by 56 publications

(70 citation statements)

References 30 publications

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“…As stated in Ref. 38, PIXE is accurate enough to detect trace impurities in bulk volume that can lead to ferromagnetism larger than that induced by the irradiation procedure. We used this technique to examine SiC wafers from different suppliers (Cree and KMT Corporation).…”

Section: Experimental Methodsmentioning

confidence: 91%

“…The impurity concentration of Fe or Ni is of the range of 10 14 /cm 3 , which corresponds to 0.015 µg/g 37 . This impurity level is around one order of magnitude lower than that of the purest graphite samples 38 , for which the origin of the defect induced magnetism is still under intensive discussion [39][40][41] . Therefore, SiC presents a suitable model system for studying defect-induced ferromagnetism in addition to carbon based materials.…”

Section: Introductionmentioning

confidence: 82%

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Disentangling defect-induced ferromagnetism in SiC

Wang

Prucnal

et al. 2014

Phys. Rev. B

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We present a detailed investigation of the magnetic properties in SiC single crystals bombarded with Neon ions. Through careful measuring the magnetization of virgin and irradiated SiC, we decompose the magnetization of SiC into paramagnetic, superparamagnetic and ferromagnetic contributions. The ferromagnetic contribution persists well above room temperature and exhibits a pronounced magnetic anisotropy. We qualitatively explain the magnetic properties as a result of the intrinsic clustering tendency of defects.2

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Section: Experimental Methodsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 82%

Disentangling defect-induced ferromagnetism in SiC

Wang

Prucnal

et al. 2014

Phys. Rev. B

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“…in our SiC substrates, we have performed PIXE using 2 MeV protons with a broad beam of around 1 mm 2 , as shown in Figure 1. PIXE is a sensitive method to detect trace impurities in bulk volume without significant structural destruction [35,39]. In the spectrum, the sharp peak is the Si K-line X-ray emission.…”

Section: A Virgin Vs Irradiated Sicmentioning

confidence: 99%

Defect-induced magnetism in SiC: Interplay between ferromagnetism and paramagnetism

et al. 2015

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Defect-induced ferromagnetism has triggered a lot of investigations and controversies. The major issue is that the induced ferromagnetic signal is so weak that it can sufficiently be accounted for by trace contamination. To resolve this issue, we studied the variation of the magnetic properties of SiC after neutron irradiation with fluence covering four orders of magnitude. A large paramagnetic component has been induced and scales up with defect concentration, which can be well accounted for by uncoupled divacancies. However, the ferromagnetic contribution is still weak and only appears in the low fluence range of neutrons or after annealing treatments. First-principles calculations hint towards a mutually exclusive role of the concentration of defects: a higher defectconcentration favors a larger magnetic interaction at the expense of spin polarization. Combining both experimental and first-principles calculation results, the defect-induced ferromagnetism can probably be understood as a local effect which cannot be scaled up with the volume. * Electronic address: s.zhou@hzdr.de 2

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“…In graphite, impurity-induced ferromagnetism has been demonstrated and has been studied theoretically. [1][2][3][4][5][6][7][8][9] The two primary contributors to this magnetism are H-complex and adatom magnetism. In H-vacancy complex magnetism, hydrogen bonds to a carbon atom near a carbon vacancy creating a new bond, thereby inducing spin polarization in an unpaired electron.…”

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confidence: 99%

Possible room-temperature ferromagnetism in hydrogenated carbon nanotubes

et al. 2010

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We find that ferromagnetism can be induced in carbon nanotubes (CNTs) by introducing hydrogen. Multiwalled CNTs grown inside porous alumina templates contain a large density of defects resulting in significant hydrogen uptake when annealed at high temperatures. This hydrogen incorporation produces H-complex and adatom magnetism which generates a sizeable ferromagnetic moment and a Curie temperature near T C =1000 K. We studied the conditions for the incorporation of hydrogen, the temperature-dependent magnetic behavior, and the dependence of the ferromagnetism on the size of the nanotubes.

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Magnetic order in graphite: Experimental evidence, intrinsic and extrinsic difficulties

Cited by 56 publications

References 30 publications

Disentangling defect-induced ferromagnetism in SiC

Disentangling defect-induced ferromagnetism in SiC

Defect-induced magnetism in SiC: Interplay between ferromagnetism and paramagnetism

Possible room-temperature ferromagnetism in hydrogenated carbon nanotubes

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