Critical properties of the quantum rotor model with phase frustration at incommensurate filling in two dimensions

Abstract

The critical properties of the zero-temperature superfluid-insulator transition in the fullyfrustrated quantum rotor model at incommensurate filling in two dimensions are studied. We develop a spherical approximation scheme for the model with phase frustration f = 1/2 by choosing a primitive unit cell composed of two sites. The finite-size scaling behavior of various physical quantities in the spherical limit provides the correlation length critical exponent nu = 0.5 and the dynamical critical exponent z = 2, which are consistent with the scenario of the generic superfluidinsulator transition even in the presence of phase frustration.