title: Restoration of the third law in spin ice thin films.
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.
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H OAH, UK.
authors.forename: L
authors.initials: L
authors.lastname: Bovo
authors.affiliation: Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ, UK.
authors.forename: X
authors.initials: X
authors.lastname: Moya
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK.
authors.forename: D
authors.initials: D
authors.lastname: Prabhakaran
authors.affiliation: 1] London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H OAH, UK [2] Department of Materials, Imperial College London, Prince Consort Rd, London SW7 2BP, UK.
authors.forename: Yeong-Ah
authors.initials: YA
authors.lastname: Soh
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK.
authors.forename: A T
authors.initials: AT
authors.lastname: Boothroyd
authors.affiliation: Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ, UK.
authors.forename: N D
authors.initials: ND
authors.lastname: Mathur
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H OAH, UK.
authors.forename: G
authors.initials: G
authors.lastname: Aeppli
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H OAH, UK.
authors.forename: S T
authors.initials: ST
authors.lastname: Bramwell