A tunable magnetic metamaterial based on the dipolar four-state Potts model
Résumé
Metamaterials, tunable artificial materials, are useful playgrounds to investigate magnetic systems. So far, artificial Ising spin systems have revealed unusual features like emergent magnetic monopoles[1,2] and charge fragmentation[3]. Here, we present a metasystem composed of a lattice of dipolarly-coupled nanomagnets. The magnetic spin of each nanomagnet is constrained to lie along a body diagonal, yielding four possible spin states. We show that the magnetic ordering of this metasystem (antiferromagnetic, ferromagnetic or spin-ice like) is determined by the spin states orientation relative to the underlying lattice. The dipolar four-state Potts model explains our experimental observations and sheds light on the role of symmetry, as well as short-and long-range dipolar magnetic interactions, in such non-Ising spin systems. Dipolar interactions in magnetic systems have been heavily studied because of their exotic physics and strongly affect essential technologies such as permanent magnets or hard disk drives [4-6]. In addition, statistical physics covers a host of applications ranging from fundamental physics to business analysis. In both cases, Ising model holds a central role. This two-spin state model has been widely used to grasp the essence of a variety of effects belonging to the field of condensed matter physics, such as phase transitions, spin glasses, magnetism, spin chains and geometric frustration. In 2006, Zhang and collaborators conducted the first experiments on artificial Ising spin systems at a
Origine | Fichiers produits par l'(les) auteur(s) |
---|
Loading...