  We present a comprehensive study of small-scale three-dimensional (3D)
tetrahedral CoFe nanostructure arrays prepared by focused electron beam-induced
deposition (FEBID) and placed in two distinct orientations with respect to the
direction of an external magnetic field. Using ultra-sensitive micro-Hall
magnetometry we obtain angular-dependent magnetic stray field hysteresis loops
that show characteristic cascading magnetic switching close to zero magnetic
field. By employing micromagnetic simulations we could reproduce the hysteresis
loops and identify characteristic field dependent magnetic configurations
including a vortex-type groundstate. From this we derive a coarse-graining
macrospin model and show that the complex switching behavior can be explained
by the reorientation dynamics of non-interacting uniaxial anisotropic magnetic
grains modeled as a superposition of Stoner-Wohlfarth particles.
