High resolution system for nanoparticles hyperthermia efficiency evaluation

A system to evaluate nanoparticles efficiency in hyperthermia applications is presented. The method allows a direct measurement of the power dissipated by the nanoparticles through the determination of the first harmonic component of the in quadrature magnetic moment induced by the applied field. The magnetic moment is measured by using an induction method. To avoid errors and reduce the noise signal a double in phase demodulation technique is used. To test the system viability we have measured nanowires, nanoparticles and copper samples of different volumes to prove by comparing experimental and modeled result

Control of magnetic properties of FeCo thin films grown by sputtering

Control of magnetic properties of FeCo thin films grown by sputterin

Synthesis of Ni nanoparticles by dc magnetron sputtering

Magnetic materials have been used with grain sizes down to the nanoscale for longer than any other type of material. The biomedical applications cover from magnetic separation of specific biological entities from their native environment to drug delivery, hyperthermia treatments or MRI contrast enhancement [1]. There are many synthesis methods depending on the final applications of the magnetic nanoparticles [2]. Sputtering methods are less extensively used, maybe due to the low efficiency of the process, however these methods have the advantage of a good control on the composition and size of the particles. Research has focused mainly on Fe [3,4], Co [5] and FeCo alloys [6]. In this work we apply the dc magnetron sputtering technique to the growth of Ni nanoparticles

Synthesis of Fe-Au nanoparticles through phase separation using the gas aggregation technique

During the last veers different type of magnetic materials have been obtained either alloys or nanopor-ritlcs with severall metalllics shells. These particle exhibt better magnetic properties, are biocompatible and have optical properties due to their shell noble metal layer, this is possible, to synthesize heterostructured nanoparticles with care/shell structure by using sputtering targets consisting of alloys of different materials. In the case of such materials have different surface energies and atomic sizes, there are diffusion processes which lead to the formation of structured nanoparticles with a shell and core having different composition. In this work we will show the results obtained about Fe-Au nanoparticles grown by I he gas aggregation technique, using magnetron sputering sources. Colloids prepared from sputtered deposits of heterostructed nanoparticles exhibit less aggregation when compared to suspensions obtained from pure magnetic materials. Spectrophotometry measurement show the presence of gold at the surface of the nanoparticles. Magnetic properties of such particle are analyzed by VSM. Compasition end structural analysis are studied by TEM and ÉDA

Fenomenologia spintronica

Breve presentación del iSOM, del GDM y sus circunstancias • A modo de introducción: Viejos experimentos con spines y corrientes • Magnetoresistencia gigante y valvulas de spin • STO’s • Memorias race-trac

Selective injection of magnetic domain walls in Permalloy nanostripes

Selective injection of magnetic domain walls in Permalloy nanostripe

Magnetic Properties of Sputtered Permalloy/Molybdenum Multilayers

In this work, we report the magnetic properties of sputtered Permalloy (Py: Ni80Fe20)/molybdenum (Mo) multilayer thin films. We show that it is possible to maintain a low coercivity and a high permeability in thick sputtered Py films when reducing the out-of-plane component of the anisotropy by inserting thin film spacers of a non-magnetic material like Mo. For these kind of multilayers, we have found coercivities which are close to those for single layer films with no out-of-plane anisotropy. The coercivity is also dependent on the number of layers exhibiting a minimum value when each single Py layer has a thickness close to the transition thickness between Neel and Bloch domain walls

Magnetic properties of sputtered permalloy/molibdenum multilayers

In this work we study the magnetic properties of Permalloy (Py: Fe20Ni80) films grown as multilayers with thin Molibdenum (Mo) spacers, in order to optimize it for sensor applications. Properties like permabillity or linearity of the loops can be controlled by growing Py as a multilayer with alternating perpendicular anisotropies [2]. However for thicknesses over 180 nm sputtered Py films develop perpendicular anisotropy (induced by the columnar morphology of the sputtered films) and the magnetic properties degrade notably [3]. Both coercive and saturating fields are nearly 10 times bigger than those measured for thinner films. Nevertheless, we found that it is possible to obtain low coercivity and high permability if thick Py films are grown as multilayers with a non-magnetic spacer between magnetic layers. In addition, we studied the effect of the layers thicknesses in the coercive field which is minimum for a Py thicknesses about 30 nm

Enhanced Exchange And Reduced Magnetization of Gd in an Fe/Gd/Fe Trilayer

The exchange interaction of Gd adjacent to Fe has been characterized by transport measurements on a double spin valve with a Fe/Gd/Fe trilayer as the middle layer. Our measurements show that the ferromagnetism of the Gd is enhanced by the presence of the Fe, and it remains ferromagnetic over its Curie temperature up to a thickness no smaller than 1 nm adjacent to the Fe. This thickness is more than double what has been reported before. Additionally, the saturation magnetization of the thin Gd layer sandwiched in Fe was found to be half of its bulk value. This reduced magnetization does not seem to be related to the proximity of Fe but rather to the incomplete saturation of Gd even for very high field

El magnetómetro por gradiente alternante de campo: una nueva herramienta para la caracterización de nanopartículas magnéticas en biofluidos y tejidos biológicos

Las aplicaciones que ofrecen las nanopartículas magnéticas basadas en sus interacciones con los campos magnéticos estáticos o variantes en el tiempo, son uno de los principales y más prometedores focos de investigación biomédica en la actualidad. La caracterización magnética de las partículas y de su comportamiento en el interior de materiales biológicos es un aspecto susceptible de numerosas mejoras, siendo además uno de los pasos preliminares fundamentales a la realización de cualquiera de los experimentos que las empleen. En este artículo se presenta una nueva herramienta que facilitará esta tarea, además de presentar futuras líneas de acción que ofrecerán nuevas posibilidades en el mundo de la nanobioingeniería, partiendo de una breve introducción teórica en la que se presentarán los principios físicos que se encuentran en la base de las aplicaciones biomédicas de las nanopartículas. Las aplicaciones que ofrecen las nanopartículas magnéticas basadas en sus interacciones con los campos magnéticos estáticos o variantes en el tiempo, son uno de los principales y más prometedores focos de investigación biomédica en la actualidad. La caracterización magnética de las partículas y de su comportamiento en el interior de materiales biológicos es un aspecto susceptible de numerosas mejoras, siendo además uno de los pasos preliminares fundamentales a la realización de cualquiera de los experimentos que las empleen. En este artículo se presenta una nueva herramienta que facilitará esta tarea, además de presentar futuras líneas de acción que ofrecerán nuevas posibilidades en el mundo de la nanobioingeniería, partiendo de una breve introducción teórica en la que se presentarán los principios físicos que se encuentran en la base de las aplicaciones biomédicas de las nanopartículas