We have investigated dynamic behavior of a three-dimensional magnetic domain wall (DW) having a Bloch-point structure in a cylindrical ferromagnetic nanowire via micromagnetic simulations. We have found the existence of an onset depinning behavior of the Bloch-point domain wall (BP-DW) motion under external magnetic fields, which is originated from overcoming an intrinsic pinning barrier generated from spin configuration of the Bloch-point domain wall inner structure. Ultrafast sequential switching of Bloch-point spins is expected to have a single precessional motion with negligible ringing on a few picoseconds time scale, which might be attractive for future spintronic applications.

Abstract. Biosynthesis of silver nanoparticles is recently attracting considerable attention because of it reduces the environmental impact and already used in numerous applications. However, the disadvantages such as easy aggregation and instability properties, prevent its' application. In this papers, biosynthesis of silver nanoparticles using aqueous extract of Diospyros discolor Willd. leaves have been prepared. The effect of biosynthesis variables, like ratio of reactants and reduction time on the particle size distribution, stability, and morphology of the silver nanoparticles were investigated. The resulted silver nanoparticles were characterized using UV spectroscopy, Transmission Electron Microscopy, and Particles Size Analyzer. Polyvinyl alcohol (PVA) was used to enhance the stability of the silver nanoparticles. Silver nanoparticles modification with 1% PVA concentration has produced a better characteristic of particle size distribution compared to the original silver nanoparticles, from highly polydisperse into moderately disperse. The results of the Zetta potential measurement also confirmed the increase stability of cluster distribution in the colloidal Ag/PVA compared to the original Ag.

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We report that a ground state spin configuration around a notch of ferromagnetic nanowires can have either symmetric or asymmetric transverse domain wall structure depending on the notch geometry by means of micromagnetic simulation with a systematic variation in the notch aspect ratio. An asymmetric off-centered domain wall configuration becomes stable for a certain range of the notch aspect ratio.