Letters to Nature

Nature 413, 48-51 (6 September 2001) | doi:10.1038/35092516; Received 14 May 2001; Accepted 20 July 2001

How 'spin ice' freezes

J. Snyder1, J. S. Slusky2, R. J. Cava2 & P. Schiffer1

  1. Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
  2. Department of Chemistry and Princeton Materials Institute, Princeton University, Princeton, New Jersey 08540, USA

Correspondence to: P. Schiffer1 Correspondence and requests for materials should be addressed to P.S. (e-mail: Email: schiffer@phys.psu.edu).

The large degeneracy of states resulting from the geometrical frustration of competing interactions is an essential ingredient of important problems in fields as diverse as magnetism1, protein folding2 and neural networks3. As first explained by Pauling4, geometrical frustration of proton positions is also responsible for the unusual low-temperature thermodynamics of ice and its measured 'ground state' entropy5. Recent work has shown that the geometrical frustration of ice is mimicked by Dy2Ti2O7, a site-ordered magnetic material in which the spins reside on a lattice of corner-sharing tetrahedra where they form an unusual magnetic ground state known as 'spin ice'6, 7, 8, 9, 10, 11, 12, 13. Here we identify a cooperative spin-freezing transition leading to the spin-ice ground state in Dy2Ti2O7. This transition is associated with a very narrow range of relaxation times, and represents a new form of spin-freezing. The dynamics are analogous to those associated with the freezing of protons in ice, and they provide a means through which to study glass-like behaviour and the consequences of frustration in the limit of low disorder.