Absence of Pauling's residual entropy in thermally equilibrated Dy sub(2)Ti sub(2)O sub(7)

The discovery of the spin-ice phase in Dy sub(2)Ti sub(2)O sub(7) numbers among the most significant findings in magnetic materials in over a decade. Spin ice has since been associated with the manifestation of magnetic monopoles and may even inform our understanding of emergent quantum electrodynam...

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Bibliographic Details
Published in:Nature physics 2013-06, Vol.9 (6), p.353-356
Main Authors: Pomaranski, D, Yaraskavitch, L R, Meng, S, Ross, KA, Noad, HML, Dabkowska, HA, Gaulin, B D, Kycia, J B
Format: Article
Language:English
Subjects:
Balancing
Deviation
Entropy
Frustration
Mathematical models
Specific heat
Spin ice
Tracking
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Summary:The discovery of the spin-ice phase in Dy sub(2)Ti sub(2)O sub(7) numbers among the most significant findings in magnetic materials in over a decade. Spin ice has since been associated with the manifestation of magnetic monopoles and may even inform our understanding of emergent quantum electrodynamics. The spin-ice model is based on an elegant analogy to Pauling's model of geometrical frustration in water ice, and predicts the same residual entropy, as confirmed by numerous measurements. Here we present results for the specific heat of Dy sub(2)Ti sub(2)O sub(7), demonstrating why previous measurements were unable to correctly capture its low-temperature behaviour. By carefully tracking the flow of heat into and out of the material, we observe a non-vanishing specific heat that has not previously been detected. This behaviour is confirmed in two samples of Dy sub(2)Ti sub(2)O sub(7), in which cooling below 0.6K reveals a deviation from Pauling's residual entropy, calling into question the true magnetic ground state of spin ice.
ISSN:1745-2473
DOI:10.1038/nphys2591