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International Journal of Modern Physics B

LINEAR RESPONSE THEORY FOR DISORDERED BOSONS

Pornthep Nisamaneephong

Published Aug 10, 2000• 0 citations
Publisher

Abstract

Within the hard-core boson model and the 1/S spin wave approximation, we have constructed the linear response theory for disordered boson system. Our numerical results shows that the instability of the superfluidity occurs when the paramagnetic part cancels out the diamagnetic part with a critical finite amout of disorder.
DOI
10.1142/s0217979200001266

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We investigate the critical phenomena of hard-core bosons in a disordered medium. Such a system is mapped onto a quantum spin-1/2 XY model with transverse random field. The system then is studied through a quantum real-space renormalization-group method. We find that randomness is always relevant in a one-dimensional (1D) system, in agreement with exact results. In two and three dimensions, there is a critical amount of disorder, below which the superfluid phase is stable. In 2D, the dynamic exponent z=1.7 for compressible states, and is close to the value of z=d as predicted by Fisher et al. $z--- is smaller for incompressible states. The correlation length exponent \ensuremath{\nu} is insensitive to z, and roughly equals 1.4. Unlike the superfluid--Mott-insulator transition without disorder, which has two distinct universality classes, we find there is only one universality class for the superfluid--Bose-glass transition.