Curie temperature of ultrathin films of fcc-cobalt epitaxially grown on atomically flat Cu(100) surfaces

Schneider, Claus M.; Bressler, P. R.; Schuster, P.; Kirschner, J.; Miguel, J. J. de; Miranda, Rodolfo

doi:10.1103/physrevlett.64.1059

Cited by 468 publications

(177 citation statements)

References 18 publications

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“…17 The absence of significant ferromagnetic response observed for Fe coverage below 3 ML may be due to three reasons: (a) the presence of a magnetic dead layer due to Fe oxidation at the top and bottom interfaces through a reaction with MgO, 24,25 as evidenced by the x-ray reflectivity, (b) Vollmer Weber growth mode 26 that for such small coverage gives rise to superparamagnetic Fe islands and (c) a Curie temperature below RT (which is the measurement temperature), which in ultrathin films does not necessarily need to coincide with the bulk value, as observed for example in Co/ Cu͑001͒. 27 To clarify this issue further, the magnetic characterization was performed ex-situ using SQUID measurements at RT as shown in the inset to Fig. 4, once a linear diamagnetic background from the MgO substrate and capping layers has been subtracted.…”

Section: The Influence Of Substrate Steps and Film Morphology On mentioning

confidence: 99%

Coverage effects on the magnetism ofFe∕MgO(001)ultrathin films

Boubeta¹,

Clavero²,

García-Martín³

et al. 2005

Phys. Rev. B

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Different aspects of the structure-magnetism and morphology-magnetism correlation in the ultrathin limit are studied in epitaxial Fe films grown on MgO(001). In the initial stages of growth the presence of substrate steps, intrinsically higher than an Fe atomic layer, prevent the connection between Fe islands and hence the formation of large volume magnetic regions. This is proposed as an explanation to the superparamagnetic nature of ultrathin Fe films grown on MgO in addition to the usually considered islanded, or Vollmer-Weber, growth. Using this model, we explain the observed transition from superparamagnetism to ferromagnetism for Fe coverages above 3 monolayers (ML). However, even though ferromagnetism and magnetocrystalline anisotropy are observed for 4 ML, complete coverage of the MgO substrate by the Fe ultrathin films only occurs around 6 ML as determined by polar Kerr spectra and simulations that consider different coverage situations. In annealed 3.5 ML Fe films, shape or configurational anisotropy dominates the intrinsic magnetocrystalline anisotropy, due to an annealing induced continuous to islanded morphological transition. A small interface anisotropy in thicker films is observed, probably due to dislocations observed at the Fe/ MgO͑001͒ interface.

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Section: The Influence Of Substrate Steps and Film Morphology On mentioning

confidence: 99%

Coverage effects on the magnetism ofFe∕MgO(001)ultrathin films

Boubeta¹,

Clavero²,

García-Martín³

et al. 2005

Phys. Rev. B

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“…One is the geometric confinement on the correlation length near the critical regime. It becomes significant for nano-sized particles, causing a reduction in the ferromagnetic ordering temperature, T C , according to the power law, [18][19][20][21][22]. In the expression, T C (∞) is the Curie temperature for the bulk and T C (d), for nanoparticles with diameter d, ξ 0 is the correlation length and λ = 1/ν with ν the critical exponent.…”

Section: Eq (3) It Indicates That T B Is Proportional To the Potentmentioning

confidence: 99%

Effect of temperature-dependent shape anisotropy on coercivity for aligned Stoner-Wohlfarth soft ferromagnets

Chen

2007

Phys. Rev. B

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The temperature variation effect of shape anisotropy on the coercivity, H C (T), for the aligned Stoner-Wohlfarth (SW) soft ferromagnets, such as fcc Ni, fcc Co and bcc Fe, are investigated within the framework of Néel-Brown (N-B) analysis. An extended, by introducing a single dimensionless correction function, the reduced magnetization,, in which τ = T/T C is the reduced temperature, M S (T) is the saturation magnetization, and T C is the Curie temperature. The factor, m(τ), accounts for the temperature-dependent effect of the shape anisotropy. The constants, H 0 and E 0 , are for the switching field at zero temperature and the potential barrier at zero field, respectively. According to this newly derived equation, the blocking temperature 2 above which the properties of superparamagnetism show up is described by the expression, T B = E 0 m 2 (τ Β )/[k B ln(t/t 0 )], with the extra correction factor m 2 (τ Β ). The possible effect on H C (T) and the blocking temperature, T B , attributed to the downshift of T C resulting from the finite size effect has been discussed also.3

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“…Thin fct Co͑001͒ films are known to be ferromagnetic with T C 's above 600 K and well-defined magnetic anisotropies for thicknesses above 3-4 ML. 14,15 These properties not only permit the detection of a potential AFM order in the Mn via the direct interface exchange coupling but also make the determination of temperature dependent AFM properties possible. An AFM order of e-fct Mn is indeed demonstrated by the MOKE magnetization loops depicted in Fig.…”

mentioning

confidence: 99%

Exchange anisotropy as a probe of antiferromagnetism in expanded face-centered-tetragonal Mn(001) layers

Wieldraaijer

Jonge

2006

Applied Physics Letters

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Manganese (Mn) grows coherent and with an expanded metastable face-centered-tetragonal (e-fct) structure on ultrathin fct Co(001)∕Cu(001) template layers. From the temperature dependence of the observed unidirectional Mn∕Co interface exchange anisotropy, an antiferromagnetic state with a blocking temperature around 410K is found for a 21 monolayer thick e-fct Mn(001) film. The temperature dependent coercivity enhancement of the Co films, which is induced by the proximity of the antiferromagnetic Mn layer, suggests a Néel temperature above 410K for this Mn phase.

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Curie temperature of ultrathin films of fcc-cobalt epitaxially grown on atomically flat Cu(100) surfaces

Cited by 468 publications

References 18 publications

Coverage effects on the magnetism ofFe∕MgO(001)ultrathin films

Coverage effects on the magnetism ofFe∕MgO(001)ultrathin films

Effect of temperature-dependent shape anisotropy on coercivity for aligned Stoner-Wohlfarth soft ferromagnets

Exchange anisotropy as a probe of antiferromagnetism in expanded face-centered-tetragonal Mn(001) layers

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