Search results for "Sky"
showing 10 items of 1603 documents
Magnetic Direct-Write Skyrmion Nanolithography
2020
Magnetic skyrmions are stable spin textures with quasi-particle behavior and attract significant interest in fundamental and applied physics. The metastability of magnetic skyrmions at zero magnetic field is particularly important to enable, for instance, a skyrmion racetrack memory. Here, the results of the nucleation of stable skyrmions and formation of ordered skyrmion lattices by magnetic force microscopy in (Pt/CoFeSiB/W)n multilayers, exploiting the additive effect of the interfacial Dzyaloshinskii-Moriya interaction, are presented. The appropriate conditions under which skyrmion lattices are confined with a dense two-dimensional liquid phase are identified. A crucial parameter to con…
Spin-transfer torque driven motion, deformation, and instabilities of magnetic skyrmions at high currents
2020
In chiral magnets, localized topological magnetic whirls, magnetic skyrmions, can be moved by spin polarized electric currents. Upon increasing the current strength, with prospects for high-speed skyrmion motion for spintronics applications in mind, isolated skyrmions deform away from their typical circular shape. We analyze the influence of spin-transfer torques on the shape of a single skyrmion, including its stability upon adiabatically increasing the strength of the applied electric current. For rather compact skyrmions at uniaxial anisotropies well above the critical anisotropy for domain wall formation, we find for high current densities that the skyrmion assumes a non-circular shape …
Thin Film Skyrmionics
2022
In condensed matter physics, magnetic skyrmions, topologically stabilized magnetic solitons, have been discovered in various materials systems, which has intrigued the community in terms of not only fundamental physics but also with respect to engineering applications. In particular, skyrmions in thin films are easily manipulable by electrical means even at room temperature. Concomitantly, a variety of possible applications have been proposed and proof-of-concept devices have been demonstrated. Recently, the field of skyrmion-based electronics has been referred to as skyrmionics and this field has been rapidly growing and extended in multiple directions. This review provides recent progres…
Dynamics and inertia of skyrmionic spin structures
2015
Understanding the motion of magnetic skyrmions is essential if they are to be used as information carriers in devices. It is now shown that topological confinement endows the skyrmions with an unexpectedly large mass, which plays a key role in their dynamics.
Dynamics and topological mass of skyrmionic spin structures (presentation video)
2014
Skyrmions are topologically protected particle-like configurations, with a topological complexity described by their Skyrmion number. In magnetic systems, they have been numerically predicted to exhibit rich dynamics, such as the gyrotropic and breathing modes, dominated by their topology. Recent experimental advances brought their static manipulation well under control. However, their dynamical behaviour is largely unexplored experimentally. In this work, we provide with the first direct observation of eigenmode skyrmion dynamics. In particular, we present dynamical imaging data with high temporal and spatial resolution to demonstrate the GHz gyrotropic mode of a single skyrmion bubble, as…
High Precision Astrometry Over Large Angular Scales with Closure Constraints: The Triplet 1803+784/1928+738/2007+777
1996
The technique of differential astrometry using the phase-delay VLBI observable promises fractional precisions of ~2 × 10−9 in the determination of the separation of sources 5° or 6° apart on the sky (Guirado et al. 1995a; Lara et al. 1996). In our present research we seek further improvement in this technique through using triplets of radio sources, which provide a closure constraint in the determination of relative angular positions. This constraint not only eases the resolution of the phase-cycle ambiguities (a major problem in the least-squares approach to astrometry with phase delays), but it also strongly constrains the space of allowable parameter values.
Role of Sky-gardens in Improving Energy Performance of Tall Buildings
2018
Natural ventilation has been used as a passive strategy for many decades but only now its importance in tall buildings for addressing the issues of high energy usage and reducing carbon footprints is emerging. Sky-gardens can play an important role in successful implementation of natural ventilation through amplification of natural wind speeds. This study presents a state-of-the-art review on optimization of tall buildings energy performance through incorporation of sky-gardens. Pros and cons of use of natural ventilation for multi-story buildings are highlighted. Details of involved technical difficulties and barriers in the construction and operation process of sky-gardens are also given.…
Survey on energy drink consumption among the adult population in sicily: Do new drinking habits associate with the risk of alcoholism in the Crib of …
2017
Background: The market for and the level of energy drinks (EDs) consumption are increasing every year, and while only a few have a comprehensive knowledge about the potential harmful physiological and psychological effects of EDs, the number of publications that have documented the potential adverse risks associated with the use of these beverages remains small. Objectives: The present study aim to evaluate the prevalence of EDs consumers among the adult population and to verify the factors associated with its consumption and onset of adverse events. Patients and Methods: A cross-sectional survey was conducted using a knowledge, attitudes, and practices (KAP) semi-structured questionnaire, …
Correlates of the non-use of contraception among female university students in Italy
2021
The present paper scrutinizes the correlates of the non-use of contraception among young women in Italy. To this end we consulted two releases of Selfy (Sexual and Emotional LiFe of Youths) survey, which offer information for a nationally sample of university students. The results reveal that the likelihood of non-using contraception is higher among women living in the South and among those with previous experience of unsafe sexual behaviours. The risk of unprotected sex is also higher within a group of students who are relatively older than the others and live in a stable cohabiting union.
Regular and singular pulse and front solutions and possible isochronous behavior in the Extended-Reduced Ostrovsky Equation: Phase-plane, multi-infin…
2016
In this paper we employ three recent analytical approaches to investigate several classes of traveling wave solutions of the so-called extended-reduced Ostrovsky Equation (exROE). A recent extension of phase-plane analysis is first employed to show the existence of breaking kink wave solutions and smooth periodic wave (compacton) solutions. Next, smooth traveling waves are derived using a recent technique to derive convergent multi-infinite series solutions for the homoclinic orbits of the traveling-wave equations for the exROE equation. These correspond to pulse solutions respectively of the original PDEs. We perform many numerical tests in different parameter regime to pinpoint real saddl…