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APS » Journals » Phys. Rev. Lett. » Volume 102 » Issue 19
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Phys. Rev. Lett. 102, 197201 (2009) [4 pages]

Quantum Effects in a Weakly Frustrated S=1/2 Two-Dimensional Heisenberg Antiferromagnet in an Applied Magnetic Field

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N. Tsyrulin1,2, T. Pardini3, R. R. P. Singh3, F. Xiao4, P. Link5, A. Schneidewind5,6, A. Hiess7, C. P. Landee4, M. M. Turnbull8, and M. Kenzelmann1,9
1Laboratory for Solid State Physics, ETH Zurich, CH-8093 Zurich, Switzerland
2Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institute, CH-5232 Villigen, Switzerland
3Department of Physics, University of California, Davis, Davis, California 95616, USA
4Department of Physics, Clark University, Worcester, Massachusetts 01610, USA
5Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), D-85747 Garching, Germany
6Institut für Festkörperphysik, TU Dresden, D-01062 Dresden, Germany
7Institut Laue-Langevin, Boîte Postale 156, F-38042 Grenoble, France
8Carlson School of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610, USA
9Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen, Switzerland

Received 22 December 2008; published 14 May 2009

We have studied the two-dimensional S=1/2 square-lattice antiferromagnet Cu(pz)2(ClO4)2 (where pz denotes pyrazine), using neutron inelastic scattering and series expansion calculations. We show that the presence of antiferromagnetic next-nearest-neighbor interactions enhances quantum fluctuations associated with resonating valence bonds. Intermediate magnetic fields lead to a selective tuning of resonating valence bonds and a spectacular inversion of the zone-boundary dispersion, providing novel insight into 2D antiferromagnetism in the quantum limit.

© 2009 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.102.197201
DOI:
10.1103/PhysRevLett.102.197201
PACS:
75.45.+j, 75.40.Mg, 78.70.Nx
 
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