Continuous and discontinuous quantum phase transitions in a model two-dimensional magnet
Abstract
The Shasty-Sutherland model, which consists of a set of spin 1/2 dimers on a 2D square lattice, is simple and soluble but captures a central theme of condensed matter physics by sitting precariously on the quantum edge between isolated, gapped excitations and collective, ordered ground states. We compress the model Shastry-Sutherland material, SrCu_2(BO_3)_2, in a diamond anvil cell at cryogenic temperatures to continuously tune the coupling energies and induce changes in state. High-resolution X-ray measurements exploit what emerges as a remarkably strong spin-lattice coupling to both monitor the magnetic behavior and the absence or presence of structural discontinuities. In the low-pressure spin-singlet regime, the onset of magnetism results in an expansion of the lattice with decreasing temperature, which permits a determination of the pressure-dependent energy gap and the almost isotropic spin-lattice coupling energies. The singlet-triplet gap energy is suppressed continuously with increasing pressure, vanishing completely by 2 GPa. This continuous quantum phase transition is followed by a structural distortion at higher pressure.
Additional Information
Copyright © 2012 National Academy of Sciences. Edited by Bertrand I. Halperin, Harvard University, Cambridge, MA, and approved December 22, 2011 (received for review September 2, 2011). Published ahead of print January 30, 2012. We are grateful to Y. Feng for helpful discussions. The work at the University of Chicago was supported by National Science Foundation (NSF) Grant DMR-0907025. D.M.S. acknowledges support from US Department of Energy (DOE), Basic Energy Sciences Grant DEFG02-99ER45789. Use of APS is supported by the US DOE Office of Basic Energy Sciences. Author contributions: S.H. and T.F.R. designed research; S.H., B.D.G., and H.A.D. grew samples; S.H., A.B., J.C.L, and G.S. performed research; S.H., A.B., D.M.S., and T.F.R. analyzed data; and S.H., A.B., D.M.S., and T.F.R. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.Attached Files
Published - PNAS-2012-Haravifard-2286-9.pdf
Submitted - 1201.3532.pdf
Files
Name | Size | Download all |
---|---|---|
md5:3ecd8c5d3dc7175ee401099b32cb4930
|
1.3 MB | Preview Download |
md5:ddc51dfef0c659861307ea3ea3ff65d6
|
372.1 kB | Preview Download |
Additional details
- PMCID
- PMC3289308
- Eprint ID
- 46925
- Resolver ID
- CaltechAUTHORS:20140707-163024874
- NSF
- DMR-0907025
- Department of Energy (DOE)
- DEFG02-99ER45789
- Created
-
2014-07-09Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field