arXiv subjects

Fabio S. Nascimento

Publications and source records attributed to Fabio S. Nascimento.

3 recordsLinked to original sources

arXiv2025

Energetics and thermodynamics of bilayer rectangular artificial spin ices

Bilayer rectangular artificial spin ices (BRASIs) with distinct aspect ratios, $γ$, are considered. Namely, we investigate how the underlying geometry modifies the interaction between two rectangular artificial spin ice layers separated by a height offset, $h$, whenever compared to the square case. Actually, rectangular layers interact by means of a Buckingham-like potential, whereas in the square case, one has an algebraic (van der Walls-like) interaction. In addition, Moiré patterns for BRASIs are less definite than for the square bilayer. We also deal with their basic thermodynamics, showing the behavior of the specific heat as a function of temperature and $γ$ for a number of height offsets.

cond-mat.other↗

arXiv2021

Bilayer artificial spin ice: magnetic force switching and basic thermodynamics

We study an artificial spin ice system consisting of two identical layers separated by a height offset $h$. For small separation, the layers are shown to attract each other, provided the whole system is in the ground state. Such an attraction comes about by means of a power-law force that we compare to van der Waals forces. When magnetic monopoles occur in one (or both) layers, the scenario becomes even more interesting and these layers may also repel each other. By tuning parameters like $h$ and monopole distance, switching between attraction and repulsion may be accomplished in a feasible way. Regarding its thermodynamics, the specific heat peak shifts to lower temperature as $h$ increases.

cond-mat.mes-hall↗

arXiv2018

Superferromagnetism and domain-wall topologies in artificial 'pinwheel' spin ice

For over ten years, arrays of interacting single-domain nanomagnets, referred to as artificial spin ices, have been engineered with the aim to study frustration in model spin systems. Here, we use Fresnel imaging to study the reversal process in 'pinwheel' artificial spin ice, a modified square ASI structure obtained by rotating each island by some angle about its midpoint. Our results demonstrate that a simple 45° rotation changes the magnetic ordering from antiferromagnetic to ferromagnetic, creating a superferromagnet which exhibits mesoscopic domain growth mediated by domain wall nucleation and coherent domain propagation. We observe several domain-wall configurations, most of which are direct analogues to those seen in continuous ferromagnetic films. However, novel charged walls also appear due to the geometric constraints of the system. Changing the orientation of the external magnetic field allows control of the nature of the spin reversal with the emergence of either 1-D or 2-D avalanches. This unique property of pinwheel ASI could be employed to tune devices based on magnetotransport phenomena such as Hall circuits.

cond-mat.dis-nn↗