3D nanonetworks promise a new era in modern solid-state physics with many applications in photonics, biomedicine, and x-electronics. Realization of 3D magnetic nanostructures could enable ultra-fast, low-power data storage devices. Due to the competing magnetic interactions in these systems, magnetic or magnetic monopolar charges can appear, which can be used as moving binary information carriers. Researchers at the University of Vienna have now designed the first 3D artificial snow lattice that contains uncorrelated magnetic charges. The results are published in the journal npj math material Provides the first theoretical proof, in the new lattice, that magnetic monopoles are stable at room temperature and can be oriented on demand by external magnetic fields.
An emerging magnetic monopole is observed in a class of magnetic materials called icy spins. However, the atomic scales and low temperatures required for its stability limit its controllability. This led to the development of two-dimensional artificial spinning ice, in which single atomic moments are replaced by magnetic nano-islands arranged on different lattices. The expansion allowed the study of the emerging magnetic monopole on accessible platforms. Reversing the magnetic direction of certain nanoislands causes the monopoles to propagate one vertex farther, leaving a trail. This trace, Dirac Strings, necessarily stores energy and binds monopoles, limiting their mobility.
Researchers around Sabri Coraltan and Florian Slanovic, led by Dieter Suisse at the University of Vienna, have designed the first artificial 3D glacier network that combines the advantages of both atomic and 2D artificial spin ice.
In collaboration with the Magnetic Nanoscale and Magnonics Group from the University of Vienna, and the Theoretical Department of Los Alamos Laboratory in the USA, the benefits of the new network have been studied using micro-magnetic simulations. Here, 2D flat nano-islands are replaced by magnetic rotational ellipsoids, and a high-symmetry 3D lattice is used. “As the ground state decays, the tension of the Dirac tendons fades away from the magnetic monomers,” says Sabri Koraltan, one of the study’s first authors. The researchers took the study to the next step, where in their simulations, magnetic monopoles propagated across the network by applying external magnetic fields, demonstrating their application as information carriers in a three-dimensional magnetic nanonetwork.
“We take advantage of the third dimension and high symmetry in the new lattice to decouple magnetic monopoles, and move them in the desired directions, almost like real electrons,” adds Sabri Coraltan. Other first author Florian Slanovek concludes that “the thermal stability of the monopoles around room temperature and above could lay the foundation for a pioneering new generation of 3D storage technologies.”
Reference: “Stress-free Dirac chains and directed magnetic charges in 3D artificial rotating ice” by Sabri Coraltan, Florian Slanovic, Florian Bruckner, Cristiano Nisoli, Andrei F. Chomak, Oleksandr F. Dobrovolsky, Claes Appert, and Dieter Suiss, August 5, 2021 And npj math material.
DOI: 10.1038 / s41524-021-00593-7