Spin Bose-Metal and Valence Bond Solid Phases in a Spin-1/2 Model with Ring Exchanges on a Four-Leg Triangular Ladder
We study a spin-1/2 system with Heisenberg plus ring exchanges on a four-leg triangular ladder using the density matrix renormalization group and Gutzwiller variational wave functions. Near an isotropic lattice regime, for moderate to large ring exchanges we find a spin Bose-metal phase with a spinon Fermi sea consisting of three partially filled bands. Going away from the triangular towards the square lattice regime, we find a staggered dimer phase with dimers in the transverse direction, while for small ring exchanges the system is in a featureless rung phase. We also discuss parent states and a possible phase diagram in two dimensions.
Additional Information© 2011 American Physical Society. Received 7 November 2010; revised manuscript received 28 January 2011; published 12 April 2011. This work was supported by NSF Grants No. DMR-0529399 (M. S. B. and M. P. A. F.), DMR-0611562, 0906816 and MRI-0958596 (D. N. S.), DMR-0907145 (O. I. M), and the A. P. Sloan Foundation (O. I. M.).
Published - Block2011p13655Phys_Rev_Lett.pdf