Magnetic Charge Propagation upon a 3D Artificial Spin-ice

Abstract

Magnetic charge propagation1-3 in the bulk frustrated materials known as spin-ice has yielded a paradigm shift in science, allowing the symmetry between electricity and magnetism to be studied in condensed matter systems. Artificial spin-ice materials4, arrays of frustrated nanostructured magnetic islands, have been produced in a range of sophisticated geometries5. These systems provide a powerful insight into the physics of frustration but do not capture the exact 3D geometry of the spin-ice lattice, meaning it is not possible to explore monopole transport upon the surface, where the lattice symmetry is broken. In this talk we will detail the direct imaging of magnetic charge propagation upon a 3D nanostructured diamond-bond lattice (Fig 1), capturing the geometry of bulk systems. Vastly different magnetic charge dynamics are observed along two principle lattice directions. Applying a field along the [110] direction leads to a small number of distant magnetic charges within the measured area. In contrast, a field along [-110] leads to a larger number of closely spaced monopole-antimonopole pairs. We will discuss these results by referring to detailed Monte-Carlo simulations and calculations which illuminate the importance of the surface coordination in determining the monopole effective chemical potential.