Sources of experimental errors in the observation of nanoscale magnetism

García, M. A.; Pinel, E. Fernández; Venta, J. de la; Quesada, A.; Bouzas, V.; Fernández, J. F.; Romero, J.J.; Martín‐González, Marisol; Costa-Kramer, J.L.

doi:10.1063/1.3060808

Cited by 195 publications

(161 citation statements)

References 27 publications

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“…44 When measuring small signals ͑below 10 −4 emu͒, magnetic traces are introduced in our samples when handling them or due to impurities in the sample substrates, so they must be considered in the analysis. Therefore, as the enhanced magnetic moment was only found in the case of SQUID and VSM measurements, and PNR and XMCD are insensitive to the substrate, a study of the MgO substrates is strongly required.…”

Section: Resultsmentioning

confidence: 99%

Origin of the giant magnetic moment in epitaxialFe3O4thin films

et al. 2010

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We study the enhanced magnetic moment observed in epitaxial magnetite ͑Fe 3 O 4 ͒ ultrathin films ͑t Ͻ 15 nm͒ grown on MgO ͑001͒ substrates by means of pulsed laser deposition. The Fe 3 O 4 ͑001͒ thin films exhibit high crystallinity, low roughness, and sharp interfaces with the substrate, and the existence of the Verwey transition at thicknesses down to 4 nm. The evolution of the Verwey transition temperature with film thickness shows a dependence with the antiphase boundaries density. Superconducting quantum interference device ͑SQUID͒ and vibrating sample magnetometry measurements in ultrathin films show a magnetic moment much higher than the bulk magnetite value. In order to study the origin of this anomalous magnetic moment, polarized neutron reflectivity ͑PNR͒, and x-ray magnetic circular dichroism ͑XMCD͒ experiments have been performed, indicating a decrease in the magnetization with decreasing sample thickness. X-ray photoemission spectroscopy measurements show no metallic Fe clusters present in the magnetite thin films. Through inductively coupled plasma mass spectroscopy and SQUID magnetometry measurements performed in commercial MgO ͑001͒ substrates, the presence of Fe impurities embedded within the substrates has been observed. Once the substrate contribution has been corrected, a decrease in the magnetic moment of magnetite thin films with decreasing thickness is found, in good agreement with the PNR and XMCD measurements. Our experiments suggest that the origin of the enhanced magnetic moment is not intrinsic to magnetite but due to the presence of Fe impurities in the MgO substrates.

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Section: Resultsmentioning

confidence: 99%

Origin of the giant magnetic moment in epitaxialFe3O4thin films

et al. 2010

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“…All possible sources of experimental errors described in Ref. 9 were considered and avoided. Samples ͑always handled with nonmetallic tools͒ were placed into a gelatin capsule and mounted on straws.…”

Section: Methodsmentioning

confidence: 99%

Evidence of intrinsic magnetism in capped ZnO nanoparticles

et al. 2010

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We present here direct experimental evidence of the magnetic polarization of Zn atoms in ZnO nanoparticles capped with different materials by means of x-ray magnetic circular dichroism ͑XMCD͒. Our results demonstrate that the magnetism in this material is intrinsic and relays in the ZnO conduction band. The analysis of both x-ray absorption spectroscopy and XMCD signals points out the formation of a well-defined interface between ZnO and the capping molecule in which the exotic magnetism arises at the hybridized band formed among Zn and the bonding atom of the molecule. The magnetic properties of these systems should critically depend on the details of this interface which may offer a new insight into the different observations for seemingly identical materials.

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“…On the other hand, a number of experimental artifacts may produce spurious results due to extrinsic effects. 22,23 Because of this, it is imperative to perform magnetic measurements which are impervious to many experimental artifacts of which bulk measurements suffer, and to use techniques that are intrinsically sensitive to interface magnetism.…”

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confidence: 99%

Upper Limit to Magnetism inLaAlO3/SrTiO3Heterostructures

et al. 2011

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Abstract-Using polarized neutron reflectometry (PNR) we measured the neutron spin dependent reflectivity from four LaAlO 3 /SrTiO 3 superlattices. This experiment implies that the upper limit for the magnetization induced by an 11 T magnetic field at 1.7 K is 2 emu/cm 3 . SQUID magnetometry of the superlattices sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO 3 and SrTiO 3 .

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Sources of experimental errors in the observation of nanoscale magnetism

Cited by 195 publications

References 27 publications

Origin of the giant magnetic moment in epitaxialFe3O4thin films

Origin of the giant magnetic moment in epitaxialFe3O4thin films

Evidence of intrinsic magnetism in capped ZnO nanoparticles

Upper Limit to Magnetism inLaAlO3/SrTiO3Heterostructures

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