Artificial 'spin ice' in a geometrically frustrated lattice of nanoscale ferromagnetic islands

摘要

We report an artificial geometrically frustrated magnet based on an array oflithographically fabricated single-domain ferromagnetic islands. The islandsare arranged such that the dipole interactions create a two-dimensionalanalogue to spin ice. Images of the magnetic moments of individual elements inthis correlated system allow us to study the local accommodation offrustration. We see both ice-like short-range correlations and an absence oflong-range correlations, behaviour which is strikingly similar to thelowtemperature state of spin ice. These results demonstrate that artificialfrustrated magnets can provide an uncharted arena in which the physics offrustration can be directly visualized.