Flux-closure-domain states and demagnetizing energy determination in sub-micron size magnetic dots

Abstract

We used single-crystalline Fe dots self-assembled under UHV as a model system to discuss micromagnetic properties of sub-micron size magnetic dots and show what properties may or may not be scaled down from macroscopic samples. Landau and diamond states were identified by MFM and reproduced by simulations. These states are surprisingly well reproduced by the the Van den Berg model despite the small dots'size. On the contrary, it is argued theoretically that the usual determination procedure of demagnetizing factors Ni's using initial susceptibility or the over-loop area underestimate the real values of Ni's in sub-micron size dots. This point is confirmed both experimentally and in simulations.

Flux-closure pattern in a two-dimensional NbN–Fe superconductor-ferromagnet nanocomposite: Anisotropy of the angular magnetoresistance

“…In addition to the small square plaquettes, there is also formation of bigger ͑Ϸ250 ϫ 250 nm 2 ͒ faceted rectangular plaquettes with facet angle of 45°. This angle matches with the facet angle of Fe islands with magnetic-flux-closure, 27,28 leading to in-plane fluxconfinement in such a way that there is very small ferromagnetic exchange interaction between them ͓Fig. 1͑b͔͒.…”

X-ray photoelectron emission microscopy in combination with x-ray magnetic circular dichroism investigation of size effects on field-induced Néel-cap reversal

“…3,8,9 The wall was studied in micron-sized elongated self-assembled Fe (110) dots, where a so-called Landau state occurs. 10 We evidence that the direction of magnetization in the Néel caps can be reversed by applying a magnetic field around 120 mT along the magnetization of the caps. This has been observed at remanence using x-ray photoelectron emission microscopy in combination with x-ray magnetic circular dichroism (XMCD-PEEM) and reproduced to a good agreement by numerical simulation.…”

Micromagnetic Modeling on self-assembled iron nanostructures

“…The dots display the shape of ingots with atomically-flat facets, bulk lattice parameter and bulk cubic magneto-crystalline anisotropy K 1 favoring < 100 > axes, however of magnitude much smaller than 1 2 µ 0 M 2 s [1]. We focus on dots approximately 600 × 300 × 60nm which display simple multi-domain states [2].…”