Critical behavior of the supersolid transition in Bose-Hubbard models
Erwin Frey, Leon Balents
We study the phase transitions of interacting bosons at zero temperature between superfluid (SF) and supersolid (SS) states. The latter are characterized by simultaneous off-diagonal long-range order and broken translational symmetry. The critical phenomena is described by a long-wavelength effective action, derived on symmetry grounds and verified by explicit calculation. We consider two types of supersolid ordering: checkerboard (X) and collinear (C), which are the simplest cases arising in two dimensions on a square lattice. We find that the SF-CSS transition is in the three-dimensional XY universality class. The SF-XSS transition exhibits nontrivial critical behavior, and appears, within a d=3-\ensuremath{\epsilon} expansion, to be driven generically first order by fluctuations. However, within a one-loop calculation directly in d=2 a strong-coupling fixed point with striking ``non-Bose-liquid'' behavior is found. At special isolated multicritical points of particle-hole symmetry, the system falls into the three-dimensional Ising universality class.
arXiv:cond-mat/9609138•Physical review. B, Condensed matter•Jan 1, 1997•51 citations