Abstract
We study the zero-temperature phase transitions of a two-dimensional disordered boson Hubbard model at incommensurate boson densities. Via matrix diagonalization and quantum Monte Carlo simulations, we construct the phase diagram and evaluate the correlation length exponent In the presence of weak disorder, we obtain the same value as that in the pure model, near the tip of a Mott insulator lobe, using the dynamical critical exponent As the strength of disorder is increased beyond a certain value, however, the value of is found to change to This result strongly suggests that there exist direct Mott insulator-to-superfluid transitions around the tip of a Mott insulator lobe in the weak disorder regime.
- Received 10 November 1998
DOI:https://doi.org/10.1103/PhysRevB.59.8420
©1999 American Physical Society