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We report the fabrication of self-organized arrays of Fe nanostripes with a lateral period of 3.5 nm by sequential deposition of Fe and Ag on Mo(110). The wires display a strong in-plane uniaxial magnetic anisotropy along their length and are superparamagnetic above TB=185±15 K. The large value of nucleation volumes, which is inferred from the analysis of the thermal dependence of coercivity below TB, suggests the existence of interactions between the wires. [ABSTRACT FROM AUTHOR]

Abstract: We report a detailed magnetic study of a new type of self-organized nanowires discussed briefly previously [B. Borca et al., Appl. Phys. Lett. 90 (2007) 142507]. The templates, prepared on sapphire wafers in a kinetically limited regime, consist of uniaxially grooved W(110) surfaces, with a lateral period here tuned to 15nm. Fe deposition leads to the formation of (110) 7nm-wide wires located at the bottom of the grooves. The effect of capping layers (Mo, Pd, Au, Al) and underlayers (Mo, W) on the magnetic anisotropy of the wires was studied. Significant discrepancies with figures known for thin flat films are evidenced and discussed in terms of step anisotropy and strain-dependent surface anisotropy. Demagnetizing coefficients of cylinders with a triangular isosceles cross-section have also been calculated, to estimate the contribution of dipolar anisotropy. Finally, the dependence of magnetic anisotropy with the interface element was used to tune the blocking temperature of the wires, here from 50 to 200K. [Copyright &y& Elsevier]

Abstract: Homoepitaxy of W(110) and Mo(110) is performed in a kinetically-limited regime to yield a nanotemplate in the form of a uniaxial array of hills and grooves aligned along the [001] direction. The topography and organization of the grooves were studied with RHEED and STM. The nanofacets, of type {210}, are tilted ∼18° away from (110). The lateral period could be varied from 4 to 12nm by tuning the deposition temperature. Magnetic nanowires were formed in the grooves by deposition of Fe at 150°C on such templates. Fe/W wires display an easy axis along [001] and a mean blocking temperature T B ≈100K. [Copyright &y& Elsevier]

A kinetic analysis of Fe islands growth on Mo(1 1 0) in the sub-monolayer range as a function of temperature is presented for the pulsed laser deposition (PLD) epitaxial technique. It has allowed us to determine the corresponding diffusion barrier Ed=0.1±0.05 eV and the diffusion attempt frequency ν0=8×1011±1 Hz. Numerical integration of the standard kinetic differential equations is used to describe the specificity of the pulsed character of PLD. Good agreement is found with experimental results. A comparison to reported molecular beam epitaxy (MBE) sub-monolayer growth of Fe at 300 K is also considered. The PLD technique is demonstrated to lead to an increase of the diffusion rate by 4 orders of magnitude, presumably as a consequence of the higher energy of the impinging species. Incidentally, this increase of diffusion rate is compensated by the large instantaneous deposition flux leading to identical densities using MBE or PLD for Fe/Mo(1 1 0) at 300 K. [Copyright &y& Elsevier]

We have fabricated 5-nm-high Fe(110) stripes by self-organized (SO) growth on a slightly vicinal R(110)/Al[sub 2]O[sub 3](1120) surface (R=Mo,W). Remanence, coercivity, and domain patterns were observed at room temperature. This contrasts with conventional SO epitaxial systems, that are superparamagnetic or even nonmagnetic at RT due to their flatness. Our process should help to overcome superparamagnetism without compromise on the lateral size if SO systems are ever to be used in applications. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]