arXiv:1410.7911 · Physical Review B
Phase diagram of the J 1 − J 2 Heisenberg model on the kagome lattice
Fabian Kolley, Stefan Depenbrock, Ian P. McCulloch, Ulrich Schollwöck, Vincenzo Alba
Abstract
We perform an extensive density-matrix renormalization-group study of the ground-state phase diagram of the spin-$1/2\phantom{\rule{0.16em}{0ex}}{J}_{1}\text{\ensuremath{-}}{J}_{2}$ Heisenberg model on the kagome lattice. We focus on the region of the phase diagram around the kagome Heisenberg antiferromagnet, i.e., at ${J}_{2}=0$. We investigate the static spin structure factor, the magnetic correlation lengths, and the spin gaps. Our results are consistent with the absence of magnetic order in a narrow region around ${J}_{2}\ensuremath{\approx}0$, although strong finite-size effects do not allow us to accurately determine the phase boundaries. This result is in agreement with the presence of an extended spin-liquid region, as it has been proposed recently. Outside the disordered region, we find that for ferromagnetic and antiferromagnetic ${J}_{2}$, the ground state displays signatures of the magnetic order of the $\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$ and the $q=0$ type, respectively. Finally, we focus on the structure of the entanglement spectrum (ES) in the $q=0$ ordered phase. We discuss the importance of the choice of the bipartition on the finite-size structure of the ES.