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Emergence of long-range order in sheets of magnetic dimers

Haravifard, S. and Banerjee, A. and van Wezel, J. and Silevitch, D. M. and dos Santos, A. M. and Lang, J. C. and Kermarrec, E. and Srajer, G. and Gaulin, B. D. and Molaison, J. J. and Dabkowska, H. A. and Rosenbaum, T. F. (2014) Emergence of long-range order in sheets of magnetic dimers. Proceedings of the National Academy of Sciences of the United States of America, 111 (40). pp. 14372-14377. ISSN 0027-8424. PMCID PMC4209985. doi:10.1073/pnas.1413318111.

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Quantum spins placed on the corners of a square lattice can dimerize and form singlets, which then can be transformed into a magnetic state as the interactions between dimers increase beyond threshold. This is a strictly 2D transition in theory, but real-world materials often need the third dimension to stabilize long-range order. We use high pressures to convert sheets of Cu^2+ spin 1/2 dimers from local singlets to global antiferromagnet in the model system SrCu_2(BO_3)_2. Single-crystal neutron diffraction measurements at pressures above 5 GPa provide a direct signature of the antiferromagnetic ordered state, whereas high-resolution neutron powder and X-ray diffraction at commensurate pressures reveal a tilting of the Cu spins out of the plane with a critical exponent characteristic of 3D transitions. The addition of anisotropic, interplane, spin–orbit terms in the venerable Shastry–Sutherland Hamiltonian accounts for the influence of the third dimension.

Item Type:Article
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Silevitch, D. M.0000-0002-6347-3513
Additional Information:© 2014 National Academy of Sciences. Edited by David D. Awschalom, The University of Chicago, Chicago, IL, and approved August 28, 2014 (received for review July 14, 2014). Published online before print September 22, 2014. We are grateful to B. H. Toby for assistance in data refinement using the General Structure Analysis System (GSAS) and to A. Dabkowski for help in preparing the single-crystal sample for high-pressure neutron scattering experiment. The work at the University of Chicago was supported by National Science Foundation Grant DMR-1206519. The work performed at the Advanced Photon Source was supported by the US Department of Energy (DOE) Office of Basic Energy Sciences under Contract DE-AC02-06CH11357 and that at the Spallation Neutron Source by the DOE Office of Basic Energy Sciences. Author contributions: S.H. and T.F.R. designed research; S.H., A.B., A.M.d.S., J.C.L., E.K., G.S., B.D.G., and J.J.M. performed research; S.H., B.D.G., and H.A.D. contributed new reagents/analytic tools; S.H., J.v.W., D.M.S., and T.F.R. analyzed data; and S.H., J.v.W., D.M.S., and T.F.R. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC02-06CH11357
Subject Keywords:condensed matter physics; quantum magnetism; phase transition; dimensional cross-over; neutron and X-ray scattering
Issue or Number:40
PubMed Central ID:PMC4209985
Record Number:CaltechAUTHORS:20140930-100130378
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Official Citation:S. Haravifard, A. Banerjee, J. van Wezel, D. M. Silevitch, A. M. dos Santos, J. C. Lang, E. Kermarrec, G. Srajer, B. D. Gaulin, J. J. Molaison, H. A. Dabkowska, and T. F. Rosenbaum Emergence of long-range order in sheets of magnetic dimers PNAS 2014 111 (40) 14372-14377; published ahead of print September 22, 2014, doi:10.1073/pnas.1413318111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50121
Deposited By: Jason Perez
Deposited On:01 Oct 2014 20:37
Last Modified:10 Nov 2021 18:52

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