Restoration of the third law in spin ice thin films.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 24619137.
- Also identified by DOI 10.1038/ncomms4439 and PMC identifier 3959195.
- Licence recorded as CC BY-NC-ND.
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Abstract
A characteristic feature of spin ice is its apparent violation of the third law of thermodynamics. This leads to a number of interesting properties including the emergence of an effective vacuum for magnetic monopoles and their currents - magnetricity. Here we add a new dimension to the experimental study of spin ice by fabricating thin epitaxial films of Dy2Ti2O7, varying between 5 and 60 monolayers on an inert substrate. The films show the distinctive characteristics of spin ice at temperatures >2 K, but at lower temperature we find evidence of a zero entropy state. This restoration of the third law in spin ice thin films is consistent with a predicted strain-induced ordering of a very unusual type, previously discussed for analogous electrical systems. Our results show how the physics of frustrated pyrochlore magnets such as spin ice may be significantly modified in thin-film samples.