Phase diagram of the antiferromagnetic XXZ model on the triangular lattice

作者：Sellmann Daniel; Zhang Xue Feng^*; Eggert Sebastian

来源：Physical Review B, 2015, 91(8): 081104.

DOI：10.1103/PhysRevB.91.081104

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 J(z). Using the density matrix renormalization group algorithm in two dimensions, we establish the locations of the phase boundaries between a plateau phase with 1/3 Neel 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 J(z) greater than or similar to 2.5J

• 出版日期2015-2-9