Possibility of direct Mott insulatortosuperfluid transitions in weakly disordered boson systems
Abstract
We study the zerotemperature phase transitions of a twodimensional 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 nu. In the presence of weak disorder, we obtain nu=0.5 + 0.1, the same value as that in the pure model, near the tip of a Mott insulator lobe, using the dynamical critical exponent z=2. As the strength of disorder is increased beyond a certain value, however, the value of nu is found to change to 0.9 + 0.1. This result strongly suggests that there exist direct Mott insulatortosuperfluid transitions around the tip of a Mott insulator lobe in the weak disorder regime.
 Publication:

arXiv eprints
 Pub Date:
 January 1999
 arXiv:
 arXiv:condmat/9901116
 Bibcode:
 1999cond.mat..1116P
 Keywords:

 Condensed Matter
 EPrint:
 5 pages, Rev Tex, 6 figures, to appear in Phys. Rev. B