Zero-point entropy in stuffed spin-ice

G. C. Lau, R. S. Freitas, B. G. Ueland, B. D. Muegge, E. L. Duncan, P. Schiffer, R. J. Cava

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


The third law of thermodynamics dictates that the entropy of a system in thermal equilibrium goes to zero as its temperature approaches absolute zero. In ice, however, a 'zero point' or residual entropy can be measured-attributable to a high degeneracy in the energetically preferred positions of hydrogen ions associated with the so-called 'ice rules'. Remarkably, the spins in certain magnetic materials with the pyrochlore structure of corner-sharing tetrahedra, called 'spin ice', have an equivalent degeneracy of energetically preferred states, and also have a zero-point entropy. Here, we chemically alter Ho"2Ti"2O"7 spin ice by 'stuffing' extra Ho magnetic moments into otherwise non-magnetic Ti sites surrounding the Ho tetrahedra. The resulting series, Ho"2(Ti 2-x Ho(x))O 7-x/2 , provides a unique opportunity to study the effects of increased connectivity between spins on a frustrated lattice. Surprisingly, the zero-point entropy per spin measured appears unchanged by these excess spins. The results suggest a chemical approach for studying ice-like frustration and other properties of the broad family of geometrically frustrated magnets based on the pyrochlore structure.

Original languageEnglish (US)
Pages (from-to)249-253
Number of pages5
JournalNature Physics
Issue number4
StatePublished - Apr 2006

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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