We have studied frustrated kagome arrays and unfrustrated honeycomb arrays of magnetostatically-interacting single-domain ferromagnetic islands with magnetization normal to the plane. The measured pairwise spin correlations of both lattices can be reproduced by models based solely on nearest-neighbor correlations. The kagome array has qualitatively different magnetostatics but identical lattice topology to previously-studied 'artificial spin ice' systems composed of in-plane moments. The two systems show striking similarities in the development of moment pair correlations, demonstrating a universality in artificial spin ice behavior independent of specific realization in a particular material system.
@article{arxiv.1207.1456,
title = {Perpendicular Magnetization and Generic Realization of the Ising Model in Artificial Spin Ice},
author = {Sheng Zhang and Jie Li and Ian Gilbert and Jason Bartell and Michael J. Erickson and Yu Pan and Paul E. Lammert and Cristiano Nisoli and K. K. Kohli and Rajiv Misra and Vincent H. Crespi and Nitin Samarth and C. Leighton and Peter Schiffer},
journal= {arXiv preprint arXiv:1207.1456},
year = {2013}
}