ROLLED-UP PERMALLOY NANOMEMBRANES WITH MULTIPLE WINDINGS

We fabricated Permalloy ( Fe 19 Ni 81) nanomembranes rolled-up into compact three-dimensional architectures and experimentally investigated their magnetic and magneto-electric responses. When a magnetic nanomembrane is rolled-up, an additional magnetostatic interaction between the multiple windings emerges. Such kind of magnetostatic interaction, unique to the rolled-up magnetic nanomembranes and not accessible in any other magnetic architecture, is addressed for the first time in this study. An important feature of rolled-up tubes with multiple windings is that the inner and outer windings are formed by a single magnetic sheet; the spin configuration therefore must be continuous. The magnetostatic interaction induces anti-parallel alignment of the spins within adjacent layers of a rolled-up nanomembrane. The interplay between the magnetostatic interaction due to geometrical transformation and the exchange coupling in the film results in a stabilization of stripe domain patterns.

Application of higher order forms for the description of electromechanical energy converters

Application of higher order forms for the description of electromechanical energy convertersThe purpose of that paper is to develop of unified equations of electromechanical energy converters accounting for the magnetic non-linearity of the main magnetic circuit of a converter. The concept of applying higher order forms of winding currents for the description of the co-energy function is introduced in order to derive the structure of converter equations via mathematical analysis. Also, another concept of equivalent magnetizing currents is applied to determine the higher order forms for selected converters designs. The structure of circuital equations for converters with multiple windings has been unified by means of the introduction of matrices of dynamic and nonlinear inductances following the higher order forms of the co-energy function.