2014/03/31 by Daniel Sellmann, Xue-Feng Zhang, Sebastian Eggert · 3 citations
Physics and Astronomy · #cond-mat.str-el #cond-mat.quant-gas
paper · pdf · doi:10.1103/physrevb.91.081104
published as Phys. Rev. B 91, 081104 (2015) · 8 pages including 13 figures with more data and more details on the 2D DMRG numerics. For the latest version and more information see http://www.physik.uni-kl.de/eggert/papers/index.html
arxiv created 2014/12/22 · arxiv updated 2015/03/04
We determine the quantum phase diagram of the antiferromagnetic spin-1/2 XXZ model on the triangular lattice as a function of magnetic field and anisotropic coupling Jz. Using the density matrix renormalization group (DMRG) algorithm in two dimensions we establish the locations of the phase boundaries between a plateau phase with 1/3 Néel order and two distinct coplanar phases. The two coplanar phases are characterized by a simultaneous breaking of both translational and U(1) symmetries, which is reminiscent of supersolidity. A translationally invariant umbrella phase is entered via a first order phase transition at relatively small values of Jz compared to the corresponding case of ferromagnetic hopping and the classical model. The phase transition lines meet at two tricritical points on the tip of the lobe of the plateau state, so that the two coplanar states are completely disconnected. Interestingly, the phase transition between the plateau state and the upper coplanar state changes from second order to first order for large values of Jz > 2.5J.