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Ground state lost but degeneracy found: the effective thermodynamics of artificial spin ice

Cristiano Nisoli·R. F. Wang·Jie Li·William F. McConville·Paul E. Lammert·Peter Schiffer·Vincent H. Crespi
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Abstract

We analyze the rotational demagnetization of artificial spin ice, a recently realized array of nanoscale single-domain ferromagnetic islands. Demagnetization does not anneal this model system into its anti-ferromagnetic ground state: the moments have a static disordered configuration similar to the frozen state of the spin ice materials. We demonstrate that this athermal system has an effective extensive degeneracy and we introduce a formalism that can predict the populations of local states in this ice-like system with no adjustable parameters.

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Cristiano Nisoli, R. F. Wang, Jie Li, William F. McConville, Paul E. Lammert, Peter Schiffer, Vincent H. Crespi. 2007-04-16. Ground state lost but degeneracy found: the effective thermodynamics of artificial spin ice. https://doi.org/10.1103/physrevlett.98.217203

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