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Originally published in Science Express on 3 September 2009
Science 16 October 2009:
Vol. 326. no. 5951, pp. 415 - 417
DOI: 10.1126/science.1177582
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Reports

Magnetic Coulomb Phase in the Spin Ice Ho2Ti2O7

T. Fennell,1,* P. P. Deen,1 A. R. Wildes,1 K. Schmalzl,2 D. Prabhakaran,3 A. T. Boothroyd,3 R. J. Aldus,4 D. F. McMorrow,4 S. T. Bramwell4

Spin-ice materials are magnetic substances in which the spin directions map onto hydrogen positions in water ice. Their low-temperature magnetic state has been predicted to be a phase that obeys a Gauss’ law and supports magnetic monopole excitations: in short, a Coulomb phase. We used polarized neutron scattering to show that the spin-ice material Ho2Ti2O7 exhibits an almost perfect Coulomb phase. Our result proves the existence of such phases in magnetic materials and strongly supports the magnetic monopole theory of spin ice.

1 Institut Laue-Langevin, Grenoble 38042, France.
2 Institut für Festkörperforschung, Forschungszentrum Juelich GmbH, Jülich Centre for Neutron Science at Institut Laue-Langevin, Grenoble 38042, France.
3 Clarendon Laboratory, Oxford Physics, Parks Road, Oxford OX1 3PU, UK.
4 London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1H 0AH, UK.

* To whom correspondence should be addressed. E-mail: fennell{at}ill.fr

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Observing Monopoles in a Magnetic Analog of Ice.
M. J. P. Gingras (2009)
Science 326, 375-376
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