Entropy-driven order in an array of nanomagnets

Long-range ordering is typically associated with a decrease in entropy. Yet, it can also be driven by increasing entropy certain special cases. We demonstrate that artificial spin ice arrays of single-domain nanomagnets designed to produce entropy-driven order. focus on the tetris structure, highly frustrated array geometry zero-point Pauli entropy, which formed selectively creating regular vacancies canonical square lattice. probe thermally active both experimentally and through simulations, measuring magnetic moments individual nanomagnets. find two-dimensional one subset these moments, we induced disorder (i.e., increased entropy) another moments. In contrast other systems, discrete degrees freedom are binary designable directly observable at microscale, system precisely calculable simulations. This example, system's interactions ground state well-defined, expands experimental landscape for study ordering.