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Bartolomé, J.; Bartolomé, Fernando; Garcı́a, L. M.; Figueroa, A. I.; Repollés, Ana; Martínez-Pérez, M. J.; Luìs, Fernando; Magén, Cesar; Selenska‐Pobell, Sonja; Pobell, F.; Reitz, Thomas; Schönemann, R.; Herrmannsdörfer, T.; Merroun, Mohamed L.; Geissler, Andrea; Wilhelm, F.; Рогалев, А.

doi:10.1103/physrevlett.109.247203

Cited by 37 publications

(44 citation statements)

References 27 publications

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“…1,5 New complexity has been introduced by the observation of ferromagnetism in undoped semiconductor thin lms and nanostructures. 13,14 Among them, magnetism in ZnO has also been studied more than that of any other compound or semiconductor. [7][8][9] Venkatesan et al 6 have observed d 0 magnetism in HfO 2 thin lms and have triggered extensive experimental activities in the eld of the room-temperature ferromagnetism of many semiconductors and nanomaterials.…”

Section: Introductionmentioning

confidence: 99%

Observation of the origin of d⁰magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

et al. 2014

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Efforts have been made to elucidate the origin of d(0) magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.

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Section: Introductionmentioning

confidence: 99%

Observation of the origin of d⁰magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

et al. 2014

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“…DOI: 10.1103/PhysRevLett.111.127202 PACS numbers: 75.75.Àc, 73.22.Àf, 75.20.En, 78.67.Qa Bulk Au is a diamagnetic material, i.e., one with a negative volume magnetic susceptibility Au . Recently, it was reported that Au nanoparticles (NPs), with functionalized surfaces, show a broad range of magnetic behavior, ranging from (enhanced) diamagnetic [1,2] to (super)paramagnetic [3][4][5] and even ferromagnetic up to room temperature [6,7]. The NP size and the type of capping molecules, strongly binding to or weakly interacting with Au, appear to influence the magnetic response.…”

mentioning

confidence: 99%

“…The NP size and the type of capping molecules, strongly binding to or weakly interacting with Au, appear to influence the magnetic response. Several explanations were suggested, such as competing magnetic contributions of the NP core and surface [3], the formation of a magnetic moment due to the exchange of charges at the Au-ligand interface [5,6,8], the creation of large orbital moments due to electron motion within surface clusters [9], and the occurrence of persistent currents in the Au core [2]. However, so far, the origin of this unexpected magnetism and why it differs strongly between different types of NPs is not yet understood [2,10,11].…”

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confidence: 99%

Giant Magnetic Susceptibility of Gold Nanorods Detected by Magnetic Alignment

et al. 2013

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We have determined the magnetic properties of single-crystalline Au nanorods in solution using an optically detected magnetic alignment technique. The rods exhibit a large anisotropy in the magnetic volume susceptibility (Á V ). Á V increases with decreasing rod size and increasing aspect ratio and corresponds to an average volume susceptibility ( V ), which is drastically enhanced relative to bulk Au. This high value of V is confirmed by SQUID magnetometry and is temperature independent (between 5 and 300 K). Given this peculiar size, shape, and temperature dependence, we speculate that the enhanced V is the result of orbital magnetism due to mesoscopic electron trajectories within the nanorods. DOI: 10.1103/PhysRevLett.111.127202 PACS numbers: 75.75.Àc, 73.22.Àf, 75.20.En, 78.67.Qa Bulk Au is a diamagnetic material, i.e., one with a negative volume magnetic susceptibility Au . Recently, it was reported that Au nanoparticles (NPs), with functionalized surfaces, show a broad range of magnetic behavior, ranging from (enhanced) diamagnetic [1,2] to (super)paramagnetic [3][4][5] and even ferromagnetic up to room temperature [6,7]. The NP size and the type of capping molecules, strongly binding to or weakly interacting with Au, appear to influence the magnetic response. Several explanations were suggested, such as competing magnetic contributions of the NP core and surface [3], the formation of a magnetic moment due to the exchange of charges at the Au-ligand interface [5,6,8], the creation of large orbital moments due to electron motion within surface clusters [9], and the occurrence of persistent currents in the Au core [2]. However, so far, the origin of this unexpected magnetism and why it differs strongly between different types of NPs is not yet understood [2,10,11].We employ a novel magnetic alignment technique to measure the magnetic properties of rod-shaped Au NPs in solution. We focus on relatively large NPs (all dimensions >7 nm) that are single crystalline. The degree of alignment is measured optically, through the magnetic field-induced linear dichroism and birefringence, across the Au surface plasmon resonance (SPR) that arises due to collective oscillation modes of the conduction electrons [12,13]. We find an enhanced (dia)magnetic behavior, which does not depend on temperature (in the range 5-300 K). We speculate that this enhanced magnetism is an orbital effect, resulting from mesoscopic electron trajectories within the NPs [2,14].The optically detected magnetic alignment technique relies on the anisotropy of both the optical and magnetic properties of the Au nanorods. Because of their shape, the rods exhibit an anisotropic optical response, determined by their longitudinal ( k ) and transverse ( ? ) polarizabilities [15]. Polarized light, therefore, provides a sensitive tool to determine the alignment of rods [16][17][18][19]. In this Letter, rod alignment is induced by a magnetic field (B) because of the difference in the magnetic susceptibility parallel ( k ) and perpendicular ( ? ) to the lo...

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“…So far the author is concerned, there are not, in the literature, magnetic moment measurements for gas phase Au 2 . Nevertheless, a magnetic moment of 2.36 BM per particle was reported [6] for deposited gold nanoparticles. It was verified that the magnetic contribution originates at the particle's Au 5d band [6].…”

Section: Resultsmentioning

confidence: 99%

“…The SE-PM6 approach was chose taking into account its minor computation time consuming and its reliability, as verified for PtF 6 [3]. The calculated values 4 were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5].…”

Section: Methodsmentioning

confidence: 99%

Explaining the magnetism of gold

Farias¹

2017

Preprint

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Strong Paramagnetism of Gold Nanoparticles Deposited on aSulfolobus acidocaldariusSLayer

Cited by 37 publications

References 27 publications

Observation of the origin of d⁰magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

Observation of the origin of d⁰magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

Giant Magnetic Susceptibility of Gold Nanorods Detected by Magnetic Alignment

Explaining the magnetism of gold

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Strong Paramagnetism of Gold Nanoparticles Deposited on aSulfolobus acidocaldariusSLayer

Cited by 37 publications

References 27 publications

Observation of the origin of d0magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

Observation of the origin of d0magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

Giant Magnetic Susceptibility of Gold Nanorods Detected by Magnetic Alignment

Explaining the magnetism of gold

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Observation of the origin of d⁰magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

Observation of the origin of d⁰magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques