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Phys. Rev. Lett. 99, 097201 (2007) [4 pages]

Evidence for Gapped Spin-Wave Excitations in the Frustrated Gd2Sn2O7 Pyrochlore Antiferromagnet from Low-Temperature Specific Heat Measurements

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J. A. Quilliam1,2, K. A. Ross1,2, A. G. Del Maestro3, M. J. P. Gingras1,4,5, L. R. Corruccini6, and J. B. Kycia1,2
1Department of Physics and Astronomy and Guelph-Waterloo Physics Institute, University of Waterloo, Waterloo, ON N2L 3G1 Canada
2Institute for Quantum Computing, University of Waterloo, Waterloo, ON N2L 3G1 Canada
3Department of Physics, Harvard University, Cambridge, Massachusetts, 02138, USA
4Canadian Institute for Advanced Research, 180 Dundas Street West, Suite 1400 Toronto, ON M5G 1Z8 Canada
5Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
6Physics Department, University of California-Davis, Davis, California 95616, USA

Received 10 May 2007; published 27 August 2007

We have measured the low-temperature specific heat of the geometrically frustrated pyrochlore Heisenberg antiferromagnet Gd2Sn2O7 in zero magnetic field. The specific heat is found to drop exponentially below approximately 350 mK. This provides evidence for a gapped spin-wave spectrum due to an anisotropy resulting from single-ion effects and long-range dipolar interactions. The data are well fitted by linear spin-wave theory, ruling out unconventional low-energy magnetic excitations in this system, and allowing a determination of the pertinent exchange interactions in this material.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.99.097201
DOI:
10.1103/PhysRevLett.99.097201
PACS:
75.50.Lk, 75.25.+z, 75.30.Ds, 75.40.Cx
 
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