Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

Figuera, Juan de la; Vergara, L.; N’Diaye, Alpha T.; Quesada, A.; Schmid, Andreas K.

doi:10.1016/j.ultramic.2013.02.020

Cited by 20 publications

(18 citation statements)

References 41 publications

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“…This is confirmed by the observation of a first order Verwey transition at 108 K, detected in a different low-energy electron microscope [22] by the 020408-3 appearance of monoclinic twins [30]. At a temperature of 128 K the sample undergoes the spin-reorientation transition exhibited by the cubic phase, detected by measurements (not shown) of the surface magnetization in spin-polarized electron microscopy.…”

supporting

confidence: 62%

“…The strong dichroic contrast is compatible with purely in-plane magnetization, as has also been detected by spinpolarized LEEM [22]. To confirm the in-plane magnetization, we perform linear dichroism (XMLD) [21].…”

mentioning

confidence: 79%

“…The sample has been aligned so the x-ray incidence (x axis of the figures) is along one of the in-plane 110 directions. For the (001) surface, those directions correspond to the projection of the 111 bulk easy axes on the surface plane, and are thus the surface easy axis directions at room temperature [22]. In consequence the circular dichroism XMCD image in Fig.…”

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confidence: 97%

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Spin and orbital magnetic moment of reconstructed2×2R45∘magnetite(001)

et al. 2015

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The surface of a magnetite single crystal with (001) orientation has been prepared by sputtering/annealing cycles providing the √ 2 × √ 2R45• reconstruction. The distribution of magnetic domains on the surface has been imaged by x-ray magnetic dichroism in a photoemission microscope. The easy axes are along the surface in-plane 110 directions. The near-surface magnetic moment was determined by applying the sum rules to XMCD spectra obtained with different kinetic energies of the secondary electrons. A reduced total moment of 3.3 μ B and a ratio of about 0.10 between orbital and spin moment was found, which we attribute to the surface reconstruction.

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confidence: 62%

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confidence: 79%

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confidence: 97%

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Spin and orbital magnetic moment of reconstructed2×2R45∘magnetite(001)

et al. 2015

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“…Magnetite (001) displays a complex multiscale magnetic domains pattern, 35,36 with arrays of lines and curved domains. The origin of such complex micromagnetic structure is the competition between the shape anisotropy and the magnetocrystalline anisotropy.…”

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confidence: 99%

Co on Fe3O4(001): Towards precise control of surface properties

Gargallo-Caballero

Martín-García

Quesada

et al. 2016

The Journal of Chemical Physics

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A novel approach to incorporate cobalt atoms into a magnetite single crystal is demonstrated by a combination of x-ray spectro-microscopy, low-energy electron diffraction, and density-functional theory calculations. Co is deposited at room temperature on the reconstructed magnetite (001) surface filling first the subsurface octahedral vacancies and then occupying adatom sites on the surface. Progressive annealing treatments at temperatures up to 733 K diffuse the Co atoms into deeper crystal positions, mainly into octahedral ones with a marked inversion level. The oxidation state, coordination, and magnetic moments of the cobalt atoms are followed from their adsorption to their final incorporation into the bulk, mostly as octahedral Co2+. This precise control of the near-surface Co atoms location opens up the way to accurately tune the surface physical and magnetic properties of mixed spinel oxides.

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“…Thus, in the (001) surface of bulk samples, the magnetization is expected to lie along the projection of the bulk h111i on the (001) surface, i.e., the in-plane h110i directions, 27 an expectation confirmed by spin-polarized low-energy electron microscopy observations (SPLEEM). 28 Most magnetic studies of thin films on SrTiO 3 are performed by techniques such as magneto-optical Kerr effect (MOKE), and SQUID or vibrating-sample magnetometry (VSM), all of which average over the full thickness of the magnetite film. 16,17,19,20,23 In most cases, h110i in-plane directions are reported for the easy-axis, 17,29,30 although some works indicate in-plane isotropic films.…”

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confidence: 99%

Room temperature in-plane ⟨100⟩ magnetic easy axis for Fe3O4/SrTiO3(001):Nb grown by infrared pulsed laser deposition

Monti¹,

Sanz²,

Oujja³

et al. 2013

Journal of Applied Physics

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We examine the magnetic easy-axis directions of stoichiometric magnetite films grown on SrTiO 3 :Nb by infrared pulsed-laser deposition. Spin-polarized low-energy electron microscopy reveals that the individual magnetic domains are magnetized along the in-plane h100i film directions. Magneto-optical Kerr effect measurements show that the maxima of the remanence and coercivity are also along in-plane h100i film directions. This easy-axis orientation differs from bulk magnetite and films prepared by other techniques, establishing that the magnetic anisotropy can be tuned by film growth. 2 It is a highly correlated electron material that presents a prototypical metal-insulator transition close to 120 K (the Verwey transition 3,4 ). At low temperature it becomes ferroelectric, and thus, multiferroic. 5,6 A bad metal at room temperature (RT), but predicted to be a half-metal with only the minority-spin band crossing the Fermi level, 7 it has been considered a promising material for spintronic applications as an spin-injector 8,9 or as part of a spin-valve.10,11 For such purposes, it is often desired to obtain highly perfect magnetite films on different oxide substrates. In particular, SrTiO 3 is a very attractive material in the microelectronics industry and can be doped to provide either an insulating or metallic substrate. In consequence, there is interest in the magnetic and transport properties of magnetite films grown on SrTiO 3 , both Nb-doped 12-16 and undoped, 17-23 by using techniques such as molecular beam epitaxy or pulsed-laser deposition (PLD).The magnetization bulk easy-axis directions of Fe 3 O 4 at RT are the cubic h111i ones. The first order anisotropy constant changes sign upon cooling to 130 K, temperature below which the easy axis are the h100i directions, [24][25][26] down to Verwey transition at $120 K where the structure changes from cubic to monoclinic. Thus, in the (001) surface of bulk samples, the magnetization is expected to lie along the projection of the bulk h111i on the (001) surface, i.e., the in-plane h110i directions, 27 an expectation confirmed by spin-polarized low-energy electron microscopy observations (SPLEEM). 28 Most magnetic studies of thin films on SrTiO 3 are performed by techniques such as magneto-optical Kerr effect (MOKE), and SQUID or vibrating-sample magnetometry (VSM), all of which average over the full thickness of the magnetite film. 16,17,19,20,23 In most cases, h110i in-plane directions are reported for the easy-axis, 17,29,30 although some works indicate in-plane isotropic films. 20 There are several reports of real-space imaging of the surface domains by magnetic-force microscopy (MFM), 16,19,23 showing domains of about 60-100 nm in size, similar to the observed grain size, but they do not identify the local domain magnetization direction. On other (100) substrates, h110i easy-axis directions are also usually reported. 31,32 Although attempts have been made to modify the easy axis orientation by the use of piezoelectric substrates 29 or through growth on ste...

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Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

Cited by 20 publications

References 41 publications

Spin and orbital magnetic moment of reconstructed2×2R45∘magnetite(001)

Spin and orbital magnetic moment of reconstructed2×2R45∘magnetite(001)

Co on Fe3O4(001): Towards precise control of surface properties

Room temperature in-plane ⟨100⟩ magnetic easy axis for Fe3O4/SrTiO3(001):Nb grown by infrared pulsed laser deposition

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