Domain wall displacement in Py square ring for single nanometric magnetic bead detection

A new approach based on the domain wall displacement in confined ferromagnetic nanostructures for attracting and sensing a single nanometric magnetic particles is presented. We modeled and experimentally demonstrated the viability of the approach using an anisotropic magnetoresistance device made by a micron-size square ring of Permalloy designed for application in magnetic storage. This detection concept can be suitable to biomolecular recognition, and in particular to single molecule detection.Comment: 8pages, 3figure

Intensity of Brillouin light scattering from spin waves in magnetic multilayers with noncollinear spin configurations: Theory and experiment

The scattering of photons from spin waves (Brillouin light scattering -- BLS) is a well-established technique for the study of layered magnetic systems. The information about the magnetic state and properties of the sample is contained in the frequency position, width, and intensity of the BLS peaks. Previously [Phys. Rev. B 67, 184404 (2003)], we have shown that spin wave frequencies can be conveniently calculated within the ultrathin film approach, treating the intralayer exchange as an effective bilinear interlayer coupling between thin virtual sheets of the ferromagnetic layers. Here we give the consequent extension of this approach to the calculation of the Brillouin light scattering (BLS) peak intensities. Given the very close relation of the BLS cross-section to the magneto-optic Kerr effect (MOKE), the depth-resolved longitudinal and polar MOKE coefficients calculated numerically via the usual magneto-optic formalism can be employed in combination with the spin wave precessional amplitudes to calculate full BLS spectra for a given magnetic system. This approach allows an easy calculation of BLS intensities even for noncollinear spin configurations including the exchange modes. The formalism is applied to a Fe/Cr/Fe/Ag/Fe trilayer system with one antiferromagnetically coupling spacer (Cr). Good agreement with the experimental spectra is found for a wide variety of spin configurations.Comment: 19 pages, 5 figure

On topological spin excitations on a rigid torus

We study Heisenberg model of classical spins lying on the toroidal support, whose internal and external radii are $r$ and $R$, respectively. The isotropic regime is characterized by a fractional soliton solution. Whenever the torus size is very large, $R\to\infty$, its charge equals unity and the soliton effectively lies on an infinite cylinder. However, for R=0 the spherical geometry is recovered and we obtain that configuration and energy of a soliton lying on a sphere. Vortex-like configurations are also supported: in a ring torus ($R>r$) such excitations present no core where energy could blow up. At the limit $R\to\infty$ we are effectively describing it on an infinite cylinder, where the spins appear to be practically parallel to each other, yielding no net energy. On the other hand, in a horn torus ($R=r$) a singular core takes place, while for $R<r$ (spindle torus) two such singularities appear. If $R$ is further diminished until vanish we recover vortex configuration on a sphere.Comment: 11 pages, 9 figure

Absence of stable collinear configurations in Ni(001)ultrathin films: canted domain structure as ground state

Brillouin light scattering (BLS) measurements were performed for (17-120) Angstrom thick Cu/Ni/Cu/Si(001) films. A monotonic dependence of the frequency of the uniform mode on an in-plane magnetic field H was observed both on increasing and on decreasing H in the range (2-14) kOe, suggesting the absence of a metastable collinear perpendicular ground state. Further investigation by magneto-optical vector magnetometry (MOKE-VM) in an unconventional canted-field geometry provided evidence for a domain structure where the magnetization is canted with respect to the perpendicular to the film. Spin wave calculations confirm the absence of stable collinear configurations.Comment: 6 pages, 3 figures (text, appendix and 1 figure added

C60/NiFe combination as a promising platform for molecular spintronics

Spintronics based on ferromagnetic metals and organic semiconductors has attracted great interest in recent years. Molecular-based spintronic devices, such as magnetic tunnel junctions, have been demonstrated with performances competing with those of conventional inorganic devices. Still, there is huge margin for improvement, as many details about the injection of spin-polarized electrons into the molecular layer remain not completely understood. In order to achieve better understanding and control of the physical mechanisms, it is necessary to explore various combinations of ferromagnetic metals and organic semiconductors. In this letter, we study the properties of the combination between the ferromagnetic metal NiFe (commonly known as Permalloy or Py) and the molecular system C60. We produced C60/Py bilayers and characterized them structurally, electrically and magnetically. The C 60 films grow smoothly on both Py and SiO2 substrates, and we estimate that a 5-nm-thick C60 film covers completely the surface underneath without leaving pinholes and can be therefore used in a vertical device, as confirmed by electrical characterization. Furthermore, the C 60 film is robust against the deposition of the top metal electrode, being the intermixing layer of only 1-2 nm at the C60/Py interface. Finally, we show that the magnetic properties of Py are not affected by the deposition sequence, and that a 5-nm-thick Py layer on top of a C60 layer keeps its magnetic properties intact. These results show that the combination between Py and C60 provides a robust template platform for the development of molecular spintronics, and can be used later on for more sophisticated investigations, such as the role of the interfaces in the spin injection.Fil: Gobbi, M.. No especifíca;Fil: Pascual, A.. No especifíca;Fil: Golmar, Federico. Instituto Nacional de Tecnología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Llopis, R.. No especifíca;Fil: Vavassori, P.. No especifíca;Fil: Casanova, F.. No especifíca;Fil: Hueso, L. E.. No especifíca

PD-0498: Use of STAT in prostate cancer: correlation with risk factors and identification of residual cohort

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Infection Related Inferior Alveolar Nerve Paresthesia in the Lower Premolar Teeth

Introduction. The aim of this paper was to describe two cases of IAN infection-induced paresthesia and to discuss the most appropriate treatment solutions. Methods. For two patients, periapical lesions that induced IAN paresthesia were revealed. In the first case, the tooth was previously endodontically treated, whereas in the second case the lesion was due to pulp necrosis. Results. For the first patient, a progressive healing was observed only after the tooth extraction. In the second patient, the paresthesia had resolved after endodontic treatment. Conclusions. The endodontic-related paresthesia is a rare complication that can be the result of a combination of etiopathogenic mechanisms such as mechanical pressure on the nerve fibers due to the expanding infectious process and the production of microbial toxins. Paresthesia resulting from periapical lesions usually subsides through elimination of infection by root canal treatment. However, if there are no signs of enhancement, the immediate extraction of the tooth is the treatment of choice in order to prevent irreversible paresthesia because it was demonstrated that there is a correlation between the duration of mechanical or chemical irritation and the risk of permanent paresthesia