Physics Department Seminar University of Alaska Fairbanks

J O U R N A L    C L U B


Emergent magnetic monopole dynamics in macroscopically degenerate artificial spin ice. 

Michael Saccone
Physics Dept, UCSC



Magnetic monopoles, proposed as elementary particles that act like isolated magnetic south- and north poles, have long captured the imagination of the research community as magnetic analogues to the electric charge. In solid state physics, a classical analogue to these elusive particles has been shown to emerge as topological excitations out of the ground state manifold of magnetic pyrochlore spin ice systems. Here, we perform the first real-time imaging of emergent magnetic monopole motion in a macroscopically degenerate artificial spin ice system consisting of thermally activated Ising-type nanomagnets that are lithographically arranged onto a pre-etched silicon substrate. This allows us to perform real-space characterization of emergent magnetic monopoles within the framework of the Debye-Hückel theory, providing unique visual evidence that these topological defects effectively act like a plasma of Coulomb-type magnetic charges. In contrast to vertex defects in two-dimensional artificial square ice, we show that emergent magnetic monopoles are free to evolve as interacting Coulombic charges within a macroscopically degenerate divergence-free vacuum, a Coulomb phase, for which we observe clear features in the form of pinch-point singularities in magnetic structure factors. I will also include some advice slides/Q and A for the undergrads.


Friday, 21 September 2018

Globe Room, Elvey Building