Remanence enhancement for stray field-based applications in arrays of crystalline nanomagnets

Resumen

With the aim of achieving stable, substantial remanences adequate for exploitation in stray field-based applications, we report on the hysteresis behavior occurring in arrays of single-crystal Fe motifs, a-beam lithographed into prisms with triangular bases and different orientations of their magnetocrystalline axes with respect to the morphological symmetry axes. From both experimental and simulational analyses we recognize the fact that the magnetization reversal processes of our samples were mediated by motif-sized vortices. Their nucleation and annihilation fields and sites within the motifs, and their field-induced displacements, are discussed in terms of the magnetocrystalline and configurational anisotropies and inter-motif dipolar interactions. From our data, we conclude that reduced remanences as large as 0.85 (sufficient for the application requirements), protected by nucleation fields of several tens of Oe, can be produced in arrays where magnetocrystalline easy axes reinforce and partly compensate the easiest and hardest configurational ones, respectively. The angular dependence of the reduced remanence associated with interplay of these anisotropies corresponds to a symmetry reduction from the triaxial one linked to the triangular morphology down to an effective uniaxial one. We also identify, for the particular case of inter-nanoprism distances that are short in comparison with the dimensions of the motif base, a contribution to the remanence enhancement originating from the dipolar interactions.