Room-temperature ferromagnetism in undoped<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>GaN</mml:mi></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>CdS</mml:mi></mml:mrow></mml:math>semiconductor nanoparticles

Madhu, Chilakapati; Sundaresan, A.; Rao, C. N. R.

doi:10.1103/physrevb.77.201306

Cited by 163 publications

(65 citation statements)

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“…Therefore, the magnitude of the saturation magnetization is in the order of 10 −1 emu/g, which is much larger than the moments of ZnObased dilute magnetic semiconductors doped with magnetic atoms 23 and is significantly larger than the measured moments originating from the broken bonds associated with the surface or atomic vacancies (typically in the order of less than 10 −3 emu/g) in pure ZnO measured using nanoparticles 24,25 or nanograined thin films. 26 However, it is quite comparable to the calculated M S of 0.069−0.34 emu/g obtained based on our first principles calculation discussed earlier, assuming the magnetic moment of 0.001−0.005 μ B /atom depending on the thickness of the nanoplates as in Table 1.…”

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confidence: 76%

Magnetism in Dopant-Free ZnO Nanoplates

et al. 2012

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It is known that bulk ZnO is a nonmagnetic material. However, the electronic band structure of ZnO is severely distorted when the ZnO is in the shape of a very thin plate with its dimension along the c-axis reduced to a few nanometers while keeping the bulk scale sizes in the other two dimensions. We found that the chemically synthesized ZnO nanoplates exhibit magnetism even at room temperature. First-principles calculations show a growing asymmetry in the spin distribution within the distorted bands formed from Zn (3d) and O (2p) orbitals with the reduction of thickness of the ZnO nanoplates, which is suggested to be responsible for the observed magnetism. In contrast, reducing the dimension along the a-or b-axes of a ZnO crystal does not yield any magnetism for ZnO nanowires that grow along c-axis, suggesting that the internal electric field produced by the large {0001} polar surfaces of the nanoplates may be responsible for the distorted electronic band structures of thin ZnO nanoplates.

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confidence: 76%

Magnetism in Dopant-Free ZnO Nanoplates

et al. 2012

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“…Following Elfimov et al [7], several theoretical papers on the high spin states of vacancies pointed out that magnetic coupling between vacancies can lead to formation of a collective ferromagnetic phase. Experimentally, ferromagnetism in semiconductors that do not contain magnetic ions was recently observed in GaN nanoparticles [40], ZnO [6], MgO [41,42], BN [43] and other crystals [41]. Based on theoretical results these authors proposed that the observed FM stems from the presence of cation vacancies.…”

Section: Implications For Experimentsmentioning

confidence: 99%

High-spin states of cation vacancies in GaP, GaN, AlN, BN, ZnO, and BeO: A first-principles study

Volnianska

Bogusławski

2011

Phys. Rev. B

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High spin states of cation vacancies in GaP, GaN, AlN, BN, ZnO and BeO were analyzed by first principles calculations. The spin-polarized vacancy-induced level is located in the band gap in GaP, ZnO and BeO. In the nitrides, the stronger exchange coupling forces the vacancy states to be resonant with valence bands, forbids formation of positively charged vacancies in GaN and BN, and allows Al vacancy in p-AlN to assume the highest possible S=2 spin state. The shape of the spin density, isotropic in the zinc blende structure, has a pronounced directional character in the wurtzite structure. Stability of spin polarization of the vacancy states is determined by spin polarization energies of anions, as well as by interatomic distances between the vacancy neighbors, and thus is given by both the lattice constant of the host and the atomic relaxations around the vacancy. Implications for experiment are discussed.

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“…The origin of magnetism in these films was not entirely clear till recently. However, recent studies on inorganic nanoparticles have shown room-temperature ferromagnetism to be a universal characteristic of these nanomaterials, typical materials exhibiting ferromagnetism being ZnO, Al 2 O 3 , MgO, GaN, and CdS, all of which are diamagnetic in bulk form [4][5][6][7]. In Fig.…”

Section: Introductionmentioning

confidence: 99%

Implications and consequences of ferromagnetism universally exhibited by inorganic nanoparticles

Sundaresan

Rao

2009

Solid State Communications

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Occurrence of surface ferromagnetism in inorganic nanoprticles as a universal property not only explains many of the unusual magnetic features of oxidic thin films, but also suggests its possible use in creating new materials, as exemplified by multiferroic BaTiO 3 nanoparticles. While the use of Mn-doped ZnO and such materials in spintronics appears doubtful, it is possible to have materials exhibiting coexistence of (bulk) superconductivity with (surface) ferromagnetism. PACS: 75.75.+a, 74.78.Na

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Room-temperature ferromagnetism in undopedGaNandCdSsemiconductor nanoparticles

Cited by 163 publications

References 32 publications

Magnetism in Dopant-Free ZnO Nanoplates

Magnetism in Dopant-Free ZnO Nanoplates

High-spin states of cation vacancies in GaP, GaN, AlN, BN, ZnO, and BeO: A first-principles study

Implications and consequences of ferromagnetism universally exhibited by inorganic nanoparticles

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