CRITICAL-BEHAVIOR OF SUPERFLUID HE-4 IN AEROGEL

We report Monte Carlo studies of the critical behavior of superfluid H e-4 in the presence of quenched disorder with long-range fractal corre lations. Modeling aerogel as an incipient percolating cluster in 3D an d weakening the bonds at the fractal sites, XY-model simulations demon strate an increase in the superfluid density exponent zeta from 0.67 /- 0.005 for the pure case to an apparent value of 0.722 +/- 0.005 in the presence of the fractal disorder, provided that the helium correla tion length does not exceed the fractal correlation length.