Properties of magnetic nanodots with perpendicular anisotropy

Nanodots with magnetic vortices have many potential applications, such as magnetic memories (VRAMs) and spin transfer nano-oscillators (STNOs). Adding a perpendicular anisotropy term to the magnetic energy of the nanodot it becomes possible to tune the vortex core properties. This can be obtained, e.g., in Co nanodots by varying the thickness of the Co layer in a Co/Pt stack. Here we discuss the spin configuration of circular and elliptical nanodots for different perpendicular anisotropies; we show for nanodisks that micromagnetic simulations and analytical results agree. Increasing the perpendicular anisotropy, the vortex core radii increase, the phase diagrams are modified and new configurations appear; the knowledge of these phase diagrams is relevant for the choice of optimum nanodot dimensions for applications. MFM measurements on Co/Pt multilayers confirm the trend of the vortex core diameters with varying Co layer thicknesses.Comment: 7 pages, 8 figure

Scaling relations for magnetic nanoparticles

A detailed investigation of the scaling relations recently proposed by [J. d'Albuquerque e Castro, D. Altbir, J. C. Retamal, and P. Vargas, Phys. Rev. Lett. 88, 237202 (2002)] to study the magnetic properties of nanoparticles is presented. Analytical expressions for the total energy of three characteristic internal configurations of the particles are obtained, in terms of which the behavior of the magnetic phase diagram for those particles upon scaling of the exchange interaction is discussed. The exponent $\eta$ in scaling relations is shown to be dependent on the geometry of the vortex core, and results for specific cases are presented.Comment: 6 pages, 4 figure

La identidad y el empoderamiento de las mujeres gambianas narrados a través de discursos fotográficos /

The article intends to explore two topics in particular: the identity construction of current Gambian women and the empowerment that they have acquired as part of the transformation process that has forced them to enter by themselves. Both topics are linked with the photographic narration as a novel way of using art studies by the construction of identity and collective empowerment as the basis of economic, political and cultural projects born from the needs of these women. The speech is analyzed in this paper is created from the horizontality of the methodology Between Voices, considering subaltern studies, gender, feminist discourses and art education.El artículo pretende abordar dos temas principalmente: la construcción de la identidad de las mujeres gambianas actuales y el empoderamiento que han adquirido como parte del proceso de transformación al que se les ha forzado a introducirse. Ambos temas se vinculan con la narración fotográfica como una manera novedosa de hacer uso de los estudios artísticos a la luz de la construcción identitaria y el empoderamiento colectivo como base de proyectos económicos, políticos y socioculturales nacidosIdentity and empowerment of gambian women narrated through photographic speeches.The article intends to explore two topics in particular: the identity construction of current Gambian women and the empowerment that they have acquired as part of the transformation process that has forced them to enter by themselves. Both topics are linked with the photographic narration as a novel way of using art studies by the construction of identity and collective empowerment as the basis of economic, political and cultural projects born from the needs of these women. The speech is analyzed in this paper is created from the horizontality of the methodology Between Voices, considering subaltern studies, gender, feminist discourses and art educatio

Vortex core size in interacting cylindrical nanodot arrays

The effect of dipolar interactions among cylindrical nanodots, with a vortex-core magnetic configuration, is analyzed by means of analytical calculations. The cylinders are placed in a N x N square array in two configurations - core oriented parallel to each other and with antiparallel alignment between nearest neighbors. Results comprise the variation in the core radius with the number of interacting dots, the distance between them and dot height. The dipolar interdot coupling leads to a decrease (increase) of the core radius for parallel (antiparallel) arrays