Size-SpecificSpin Configurations in Single Iron Nanomagnet:From Flower to Exotic Vortices.

The different spin configurationsin the vicinity of the single-domain/vortextransition are reported in isolated magnetic nanoparticles. By combiningchemical synthesis, electron holography in a dedicated transmissionelectron microscope and micromagnetic simulations, we establish the“magnetic configurations vs size” phase diagram of Fesingle-crystalline nanocubes. Room temperature high resolution magneticmaps reveal the transition between single-domain and vortex statesfor Fe nanocubes from 25 to 27 nm, respectively. An intermediate spinconfiguration consisting of an ⟨111⟩ vortex is for thefirst time evidenced. [ABSTRACT FROM AUTHOR]