Possible spin liquid phase of the S = 1/2 J1-J2 triangular Heisenberg model*

We study the $S=1/2$ Heisenberg model on the triangular lattice with nearest neighbor interaction $J_1$ and next nearest neighbor interaction $J_2$ with the density matrix renormalization group. We are able to study long open cylinders with width up to 9 lattice spacings. At $J_2/J_1=0.1$, we find a possible spin liquid (SL) state with short range spin-spin, bond-bond and chiral correlation lengths, bordered by a classical $120^\circ$ Need order pattern at small $J_2$ and a two sub-lattice collinear magnetic ordered state at $J_2 > 0.17$. We identify two quasi-degenerate ground states in the SL phase on long even cylinders, with an energy gap that decreases exponentially with the cylinder width. We also observe a dimerization effect on odd cylinders. We further find a large spin triplet gap. Our evidence supports a fully gapped SL state for the intermediate phase.