Abstract
Magnetic charge propagation in spin-ice materials has yielded a paradigm-shift in science, allowing the symmetry between electricity and magnetism to be studied. Recent work is now suggesting the spin-ice surface may be important in mediating the ordering and associated phase space in such materials. Here, we detail a 3D artificial spin-ice, which captures the exact geometry of bulk systems, allowing magnetic charge dynamics to be directly visualized upon the surface. Using magnetic force microscopy, we observe vastly different magnetic charge dynamics along two principal directions. For a field applied along the surface termination, local energetics force magnetic charges to nucleate over a larger characteristic distance, reducing their magnetic Coulomb interaction and producing uncorrelated monopoles. In contrast, applying a field transverse to the surface termination yields highly correlated monopole-antimonopole pairs. Detailed simulations suggest it is the difference in effective chemical potential as well as the energy landscape experienced during dynamics that yields the striking differences in monopole transport.
Highlights
Magnetic charge propagation in spin-ice materials has yielded a paradigm-shift in science, allowing the symmetry between electricity and magnetism to be studied
The energy scale for the production of monopoles upon the spin-ice lattice is controlled by the chemical potential (μ), which is governed by properties intrinsic to the material such as lattice constant and magnetic moment[6]
As in all ferromagnetic materials, the 3DASI studied here passes through a field-driven state whereby the component along the field is effectively demagnetized
Summary
Magnetic charge propagation in spin-ice materials has yielded a paradigm-shift in science, allowing the symmetry between electricity and magnetism to be studied. 1234567890():,; The concept of magnetic monopole transport within a condensed matter setting has captivated scientists, allowing established theory[1] to become an experimental realization[2,3,4] within the bulk pyrochlore systems known as spinice[5] In these three-dimensional (3D) systems, rare earth spins are located upon corner-sharing tetrahedra, and energy minimisation yields a local ordering principle known as the ice-rule, where two spins point into the centre of a tetrahedron and two spins point out. The arrangement of magnetic nanowires into two-dimensional lattices has recently shown to be a powerful means to explore the physics of frustration and associated emergent physics These artificial spin-ice (ASI) systems[9–15], where each magnetic nanowire behaves as an effective Ising spin, have recently yielded an experimental realisation of the square ice model[16] and have been used to study the thermal dynamics of monopoles in the context of Debye–Hückel theory[17]. MFM is harnessed to image the formation and propagation of magnetic charge upon the 3D nanowire lattice
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
