Permanent Magnetism, Magnetic Anisotropy, and Hysteresis of Thiol-Capped Gold Nanoparticles

Crespo, P.; Litrán, R.; Rojas, T.C.; Multigner, M.; Fuente, Jesús M. de la; Sánchez-López, J.C.; García, M. A.; Hernando, A.; Penadés, Soledad; Fernández, A.

doi:10.1103/physrevlett.93.087204

Cited by 533 publications

(346 citation statements)

References 18 publications

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“…In particular the magnetism seen with other methods 12 peaks at much smaller sizes on the order of 2 nm where the Fermi wave vector (k F = 1.2 nm −1 ) is close to the inverse diameter. Also the magnetism is strongly affected by capping 13 and our samples have no capping. Of course on general grounds those GNPs with an odd number of atoms (valence electrons) must have at least one Bohr magneton.…”

mentioning

confidence: 88%

“…This is often addressed by adding an organic capping layer. Magnetism is observed in thiol-capped GNPs, [12][13][14] yet it is often attributed primarily to the gold sulfur bond present in such compounds instead of the finite size of the GNP. There are only a few studies investigating magnetism in uncapped GNPs, [15][16][17][18] and with para-, ferro-, and ferrimagnetism reported, there is no consensus.…”

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confidence: 99%

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Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Dehn

Arseneau

Böni

et al. 2016

The Journal of Chemical Physics

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Chemisorption of muonium onto the surface of gold nanoparticles has been observed. Muonium (μ+e−), a light hydrogen-like atom, reacts chemically with uncapped 7 nm gold nanoparticles embedded in mesoporous silica (SBA-15) with a strong temperature-dependent rate. The addition rate is fast enough to allow coherent spin transfer into a diamagnetic muon state on the nanoparticle surface. The muon is well established as a sensitive probe of static or slowly fluctuating magnetic fields in bulk matter. These results represent the first muon spin rotation signal on a nanoparticle surface or any metallic surface. Only weak magnetic effects are seen on the surface of these Au nanoparticles consistent with Pauli paramagnetism.

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confidence: 88%

mentioning

confidence: 99%

Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Dehn

Arseneau

Böni

et al. 2016

The Journal of Chemical Physics

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“…But the particular interaction responsible for occurrence of ferromagnetic phase in these nanomaterials is still under investigation. Recently observed ferromagnetism in ferroelectric 2-6 nanomaterials, [7][8][9][10][11][12][13] makes the ferromagnetism as a trivial property of nanomaterials. 14 The most common property of these materials is that they don't have unpaired electrons in them, but still show magnetism which is counter intuitive.…”

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confidence: 99%

Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

et al. 2015

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In our earlier studies the BaTiO3 samples were processed at higher temperatures like 1000oC and explained the observed magnetism in it. It is found that the charge transfer effects are playing crucial role in explaining the observed ferromagnetism in it. In the present work the samples were processed at lower temperatures like 650oC-800oC. The carrier densities in these particles were estimated to be ∼ 1019-1020/cm3 range. The band gap is in the range of 2.53eV to 3.2eV. It is observed that magnetization increased with band gap narrowing. The higher band gap narrowed particles exhibited increased magnetization with a higher carrier density of 1.23×1020/cm3 near to the Mott critical density. This hint the exchange interactions between the carriers play a dominant role in deciding the magnetic properties of these particles. The increase in charge carrier density in this undoped BaTiO3 is because of oxygen defects only. The oxygen vacancy will introduce electrons in the system and hence more charge carriers means more oxygen defects in the system and increases the exchange interactions between Ti3+, Ti4+, hence high magnetic moment. The coercivity is increased from 23 nm to 31 nm and then decreased again for higher particle size of 54 nm. These particles do not show photoluminescence property and hence it hints the absence of uniformly distributed distorted [TiO5]-[TiO6] clusters formation and charge transfer between them. Whereas these charge transfer effects are vital in explaining the observed magnetism in high temperature processed samples. Thus the variation of magnetic properties like magnetization, coercivity with band gap narrowing, particle size and charge carrier density reveals the super paramagnetic nature of BaTiO3 nanoparticles. The nonlinear optical coefficients extracted from Z-scan studies suggest that these are potential candidates for optical imaging and signal processing applications.

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“…Particularly, the magnetic properties of clusters of 4d elements, which are non-magnetic as bulk materials, have attracted much of the attention (e.g. Kumar and Kawazoe, 2003;Shinohara et al, 2003;Sampedro et al, 2003;Litrán et al, 2006;Hernando et al, 2006c); among these 4d transition metals, gold has been the target of many investigations either as thin films with or without an organic layer on top (Carmeli et al, 2003;Reich et al, 2006), or as nanometric particles with our without capping molecules (Hori et al, 1999;Crespo et al, 2004). Despite all the efforts in this field, the permanent magnetism shown by these systems is not yet understood (Vager and Naaman, 2004;Hernando and García, 2006;Hernando et al, 2006a;Crespo et al, 2006).…”

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confidence: 99%

Electronic structure, magnetic properties, and microstructural analysis of thiol-functionalized Au nanoparticles: role of chemical and structural parameters in the ferromagnetic behaviour

et al. 2008

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Gold nanoparticles (NPs) have been stabilized with a variety of thiol-containing molecules in order to change their chemical and physical properties; among the possible capping systems, alkane chains with different lengths, a carboxylic acid and a thiol-containing biomolecule (tiopronin) have been selected as protecting shells for the synthesized NPs; the NPs solubility in water or organic solvents is determined by the protecting molecule. A full microstructural characterization of these NPs is presented in the current research work. It has been shown that NPs capped with alkanethiol chains have a marked ferromagnetic behaviour which might be also dependent on the chain length. The simultaneous presence of Au-Au and Au-S bonds together with a reduced particle diameter, and the formation of an ordered monolayer protective shell, have been proved to be key parameters for the ferromagnetic-like behaviour exhibited by thiol-functionalized gold NPs.

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Permanent Magnetism, Magnetic Anisotropy, and Hysteresis of Thiol-Capped Gold Nanoparticles

Cited by 533 publications

References 18 publications

Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

Electronic structure, magnetic properties, and microstructural analysis of thiol-functionalized Au nanoparticles: role of chemical and structural parameters in the ferromagnetic behaviour

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