Speaker
Description
Vertex-Frustrated artificial spin ice systems are two-dimensional arrays of interacting ferromagnetic elements in which the moments are arranged in certain way that not all vertices can be relaxed into their lowest energy configuration simultaneously. As a consequence, these systems have degenerate ground states that include excited vertices and degeneracy comes from the allocation of excited vertices. In such systems, a wealth of different emergent behavior in the collective dynamics of the magnetic moments can be observed by using real-space imaging techniques such as Photoemission Electron Microscopy (PEEM) and Magnetic Force Microscopy (MFM). In one example of a vertex-frustrated system, the Santa Fe lattice, the ground state degeneracy changes with the strength of interactions and the excited vertices whose fluctuations control the low energy kinetics of the moments. Here we present a study on the ground state behavior of Santa Fe lattice by performed PEEM and MFM measurements on lattices with various spacing and island moment after thermal annealing treatments. We observed a notable change in the possible ground state configurations across different lattice parameters, demonstrating that Santa Fe lattice is an excellent candidate for studying novel order induced by vertex frustration. This work is funded by the US Department of Energy, Office of Basic Energy Sciences, Materials Science and Engineering Division under grant number DE-SC0010778. Work at the University of Minnesota is supported by NSF.
