73,101 research outputs found

    Large angle magnetization dynamics measured by time-resolved ferromagnetic resonance

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    A time-resolved ferromagnetic resonance technique was used to investigate the magnetization dynamics of a 10 nm thin Permalloy film. The experiment consisted of a sequence of magnetic field pulses at a repetition rate equal to the magnetic systems resonance frequency. We compared data obtained by this technique with conventional pulsed inductive microwave magnetometry. The results for damping and frequency response obtained by these two different methods coincide in the limit of a small angle excitation. However, when applying large amplitude field pulses, the magnetization had a non-linear response. We speculate that one possible cause of the nonlinearity is related to self-amplification of incoherence, known as the Suhl instabilities.Comment: 23 pages, 8 figures, submitted to PR

    Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping

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    A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales  ~104 ωpe−1 \tilde \, 10^4 \, {\omega}_{pe}^{-1}. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well-confined to the downstream region of the electrostatic shock. The shock formation process is not modified and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock

    Symmetry-broken dissipative exchange flows in thin-film ferromagnets with in-plane anisotropy

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    Planar ferromagnetic channels have been shown to theoretically support a long-range ordered and coherently precessing state where the balance between local spin injection at one edge and damping along the channel establishes a dissipative exchange flow, sometimes referred to as a spin superfluid. However, realistic materials exhibit in-plane anisotropy, which breaks the axial symmetry assumed in current theoretical models. Here, we study dissipative exchange flows in a ferromagnet with in-plane anisotropy from a dispersive hydrodynamic perspective. Through the analysis of a boundary value problem for a damped sine-Gordon equation, dissipative exchange flows in a ferromagnetic channel can be excited above a spin current threshold that depends on material parameters and the length of the channel. Symmetry-broken dissipative exchange flows display harmonic overtones that redshift the fundamental precessional frequency and lead to a reduced spin pumping efficiency when compared to their symmetric counterpart. Micromagnetic simulations are used to verify that the analytical results are qualitatively accurate, even in the presence of nonlocal dipole fields. Simulations also confirm that dissipative exchange flows can be driven by spin transfer torque in a finite-sized region. These results delineate the important material parameters that must be optimized for the excitation of dissipative exchange flows in realistic systems.Comment: 20 pages, 5 figure

    Using mixed methods for analysing culture : The Cultural Capital and Social Exclusion project

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    This paper discusses the use of material generated in a mixed method investigation into cultural tastes and practices, conducted in Britain from 2003 to 2006, which employed a survey, focus groups and household interviews. The study analysed the patterning of cultural life across a number of fields, enhancing the empirical and methodological template provided by Bourdieu’s Distinction. Here we discuss criticisms of Bourdieu emerging from subsequent studies of class, culture and taste, outline the arguments related to the use of mixed methods and present illustrative results from the analysis of these different types of data. We discuss how the combination of quantitative and qualitative methods informed our analysis of cultural life in contemporary Britain. No single method was able to shed light on all aspects of our inquiry, lending support to the view that mixing methods is the most productive strategy for the investigation of complex social phenomena

    A Capacity Building for Higher Education ERASMUS+ Project: Strategic Human Resources Management for Southeast Asian Universities (HR4ASIA)

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    The development and optimization of Higher Education Institutions (HEIs) is becoming more and more important. Consequently, Human Resources Management (HRM) has gained greater prominence in the management of these institutions. Due to the complexity of academic contexts of HEIs, HRM models need to be able to respond to new challenges. These challenges concern selection, motivation and development of their staff. Currently, especially in Southeast Asian countries, Human Resources approaches need to be more efficient and tailored to current labor and societal needs. In order to support Higher Education organizational changes in Southeast Asia, a consortium of 4 institutions from Europe (Spain, Portugal, Italy and Lithuania) and 8 from Asia (Vietnam, Cambodia, Laos and Thailand) lead by the University of Danang (Vietnam), applied to a Capacity Building for Higher Education project under the framework of the Erasmus+ Program. The project “Strategic Human Resources Management for Southeast Asian Universities” (HR4Asia) approved in 2016 and co-funded by the European Commission aims at contributing to Higher Education organizational reform in Southeast Asia by improving HRM at the target HEIs from Cambodia, Lao PDR, Vietnam and Thailand. Each partner has well defined tasks according to the work packages established on the project. This research is focused on the competences that workers need to achieve to have a better performance in the institution. It was necessary to present and deconstruct, among others, the concepts of competence as capacity and competency as performance, to learn how to measure competencies and to manage competency and Human Resources. Staff involved in this project will be able to design and define the competencies model of the structures of each HEI to define the competency model per structure (mapping of organizational competencies and a model of competences of structures). This is one more step to achieve the following final goals: introduce in Southeast Asian HEIs a scheme to developing and implementing innovative HRM approaches, paying attention to transversal and additional skills, such as communication and self-learning. Tailor-made dissemination activities addressing non-partner HEIs, Ministries of Higher Education and other stakeholders will promote the project objectives, paving the way for its sustainability
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