Materials Science

Ising Ice

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Science  05 Oct 2012:
Vol. 338, Issue 6103, pp. 17
DOI: 10.1126/science.338.6103.17-b

Spin ice, a group of exotic magnetic materials that have molecular arrangements akin to that of water ice, can be artificially engineered out of nanomagnets arranged in patterns that resemble real crystal lattices, but with fully tunable properties. Normally, these nanomagnets orient themselves within the plane that they occupy; Zhang et al. created an artificial spin ice in which the magnetic moments point perpendicular to the plane—a realization of the canonical Ising spin model. Magnetic force microscopy confirmed that, after initialization, the magnets pointed either up or down. The frustrated kagome lattice, with perpendicular magnetization, showed similar spatial correlation properties to those of the honeycomb lattice, with in-plane moments, implying that the behavior is dominated by the nearest-neighbor interactions, which are matched between the two; the similarity was maintained through a range of interactions. The realization of perpendicular magnetization is expected to lead to interesting hybrid systems with thin films, in which the properties of the adjacent films may be controllable by the perpendicular magnetic moments.

Phys. Rev. Lett. 109, 087201 (2012).

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