We investigate a quantum phase transition between a Néel phase and a valence bond solid (VBS) phase, each of which breaks a different Z2 symmetry, in a spin-1/2 two-leg XXZ ladder with a four-spin interaction. The model can be viewed as a one-dimensional variant of the celebrated J-Q model on a square lattice. By means of variational uniform matrix product state calculations and an effective field theory, we determine the phase diagram of the model and present evidence that the Néel-VBS transition is continuous and belongs to the Gaussian universality class with the central charge c=1. In particular, the critical exponents β,η, and, ν are found to satisfy the constraints expected for a Gaussian transition within numerical accuracy. These exponents do not detectably change along the phase boundary while they are in general allowed to do so for the Gaussian class.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics