Domain wall pinning in FeCoCu bamboo-like nanowires

Abstract

The three dimensional nature of cylindrical magnetic nanowires has opened a new way to control the domain configuration as well as the magnetization reversal process. The pinning effect of the periodic diameter modulations on the domain wall propagation in FeCoCu individual nanowires is determined by Magnetic Force Microscopy, MFM. A main bistable magnetic configuration is firstly concluded from MFM images characterized by the spin reversal between two nearly single domain states with opposite axial magnetization. Complementary micromagnetic simulations confirm a vortex mediated magnetization reversal process. A non-standard variable field MFM imaging procedure allows us to observe metastable magnetic states where the propagating domain wall is pinned at certain positions with enlarged diameter. Moreover, it is demonstrated that it is possible to control the position of the pinned domain walls by an external magnetic field.

Observing growth under confinement: Sn nanopillars in porous alumina templates

“…Control and knowledge of such crystallographic parameters is known to be essential for creating and improving nanoscale devices where changes in atomic structure and crystallographic orientation can impact device performance. 5,6 Porous anodic alumina (PAA), formed by the electrochemical anodization of aluminium in various electrolytes, is a popular template for the fabrication of nanoscale devices such as magnetic storage, 7 catalytic membranes, 8 batteries, and solar cells. 9,10 The distance can be tuned by varying the anodisation voltage, and pore diameters can be chosen between 10 and 400 nm by careful selection of electrolyte composition and voltage.…”

Direct observation of transverse and vortex metastable magnetic domains in cylindrical nanowires

“…Experimental imaging of the surface magnetic state has previously been carried out at remanence or under an in situ applied magnetic field by magnetic force microscopy (MFM) [9] and magneto-optical Kerr effect (MOKE) [10]. In addition, electron holography supplies information of the magnetic flux distribution of the internal magnetic structure apart from the stray fields outside the nanowires [11,12].…”

Domain wall pinning in a circular cross-section wire with modulated diameter

“…Finally, note that experimental reports of the interaction of domain walls at modulations of diameter are still scarce and incomplete. Letting aside reports of magnetometry of large assemblies of wires still in a matrix, or experiments on single wires, however not separating the physics of nucleation from the one of going through the modulation, only a handful of reports exist of domain-walls in diameter-modulated single wires [15]. These do not provide a comprehensive quantitative picture at present.…”