Striped Spin Liquid Crystal Ground State Instability of Kagome Antiferromagnets
The Dirac spin liquid ground state of the spin 1/2 Heisenberg kagome antiferromagnet has potential instabilities. This has been suggested as the reason why it does not emerge as the ground state in large-scale numerical calculations. However, previous attempts to observe these instabilities have failed. We report on the discovery of a projected BCS state with lower energy than the projected Dirac spin liquid state which provides new insight into the stability of the ground state of the kagome antiferromagnet. The new state has three remarkable features. First, it breaks spatial symmetry in an unusual way that may leave spinons deconfined along one direction. Second, it breaks the U(1) gauge symmetry down to Z_2. Third, it has the spatial symmetry of a previously proposed "monopole" suggesting that it is an instability of the Dirac spin liquid. The state described herein also shares a remarkable similarity to the distortion of the kagome lattice observed at low Zn concentrations in Zn-paratacamite and in recently grown single crystals of volborthite suggesting it may already be realized in these materials.
© 2013 American Physical Society. Received 5 November 2012; published 1 November 2013. We acknowledge useful discussions with Matthew Fisher, Michael Hermele, Zenji Hiroi, David Huse, and Nandini Trivedi. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. OCI-1053575 and the High Performance Computing Cluster at Case Western Reserve University. B. K.C and J. M. K. contributed equally to this work.
Accepted Version - 1210.1585.pdf
Published - PhysRevLett.111.187205.pdf
Supplemental Material - kagome-supplementary-PRL-v3.pdf