1,721,016 research outputs found
Progetto PONTE dell' Istituto Nazionale per la Fisica della Materia (INFM) - Network Applicativo e Industriale
No full textLe proprietà magnetomeccaniche superiori mostrate dai materiali amorfi e la potenzialità della tecnica di misura in onde magnetoelastiche, evidenziata nell’ambito del sottoprogetto–sud SEMASTI dell’INFM, hanno dato un nuovo impulso allo sviluppo di sensori a basso costo e ad alta prestazione. Pertanto gli obiettivi di questo progetto PONTE consistono nella realizzazione di un prototipo, che lavori come accelerometro sfruttando la tecnica di misura in onde magnetoelastiche, per monitorare le vibrazioni relativamente ad opere di ingegneria civile, o parti di strutture meccaniche, e che nello stesso tempo sia economico, abbia alta sensibilità, risulti affidabile, stabile e robusto in modo da poter essere commercialmente competitivo. In questo modo viene portata a compimento una delle prospettive applicative più valide tra quelle emerse dal Progetto SEMASTI
Magnetic and structural investigation of Fe50Co50 thin films across the transition from in-plane to out-of-plane anisotropy
No full textThin Fe50Co50 (FeCo) layers have recently attracted great attention due to their high saturation magnetization, spin polarization factor and possible application in magnetic devices, showing perpendicular magnetization, as well [1]. In thin FeCo films, the growth process highly affects the features of the magnetization reversal process as compressive or tensile stress may induce an additional source of magnetic anisotropy [2]. In detail, due to their high positive magnetostrictive coefficients, the presence of a compressive stress my favour an out-of-plane orientation of the magnetization.
In this paper, we present FeCo layers grown by dc-magnetron sputtering on Si substrates in Ar atmosphere and covered by a 5 nm thick Cr overlayer to prevent oxidation. Their thickness, t, ranged from 5 nm up to 100 nm as in this range we expect to find a compressive stress [3]. Room temperature magnetization (M) data were collected using a SQUID magnetometer and a MOKE apparatus, using both an in-plane and a out-of-plane magnetic field (H). Magnetoresistance (MR) measurements were collected using the Van der Pauw method with an in-plane H and an in-plane current both parallel and perpendicular to H. The structural characterization was performed with a high resolution X-Ray diffractometer; the samples profile was investigated through an optical profilometer having a 1 nm vertical resolution.
For small values of t, the shape of the in-plane M loops is squared and the coercive field increases with t for 5 nm 20 nm the approach to saturation is slower and the shape of the whole loop gets less and less squared. MR data indicate that, for t up to 20 nm the MR effect is anisotropic in character, its intensity is small (~ 0.02 %), and saturation fields are in agreement with those measured from M loops. For t > 20 nm the MR effect becomes almost isotropic, its intensity increases of about one order of magnitude and the approach to saturation gets slower. Therefore, both techniques suggest that the magnetization reorientation process changes for t > 20 nm, and the results are in agreement with the progressive development of an out-of-plane easy axis [4]. Those results will be discussed and compared with the structural ones, in order to investigate the interplay between the developing anisotropy and the stacking of the FeCo films and to estimate the strength of the compressive stress.
[1] N. Miyamoto et al., J. Appl. Phys. 107 (2010) 09CT19.
[2] W. Yu et al., J. Appl. Phys. 99 (2006) 08B706.
[3] J. McCord et al., J. Magn. Magn. Mater. 271 (2004) 46.
[4] G. Ausanio et al., Thin Solid Films 519 (2011) 5420
Magnetisation and Deformation Effects in Composite Materials of Magnetic Microparticles Dispersed in an Elastic Matrix
No full textComposito elasto-magnetico innovativo con rigidità variabile per applicazioni nel campo dell’attenuazione delle vibrazioni
No full textBehaviour of magnetisation as a function of the strain in composities of ferromagnetic microparticles in an elastic matrix
No full textApplication of Magnetoelastic Resonators for the Monitoring and Control of Manifacturing Position
No full textElastomagnetic effect in new composite materials of oriented magnetic microparticles in a silicone matrix
No full textWeak stripe domains in Co/Fe multilayers
No full textUltra-high-vacuum electron-beam-evaporated Co/Fe multilayers (C-x/Fe-3x with x = 5, 10, 15 nm) were studied by atomic and magnetic force microscopy (AFM, MFM), vibrating sample magnetometry (VSM) and conversion electron Mossbauer spectroscopy (CEMS). MFM investigation showed long, dense and parallel domain regions (stripe domains) with the average width decreasing with the multilayer thickness. VSM and CEMS measurements showed the presence of an out-of-plane anisotropy, whose origin is ascribed to a planar stress at the interfaces, and which can give account of the observed narrow stripe domain pattern
Magnetic Properties of nanoparticle-assembled iron films with peculiar magnetic anisotropy and topological distribution
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