title: Quantum versus geometric disorder in a two-dimensional Heisenberg antiferromagnet.
abstract: We present a numerical study of the spin-1/2 bilayer Heisenberg antiferromagnet with random interlayer dimer dilution. From the temperature dependence of the uniform susceptibility and a scaling analysis of the spin correlation length we deduce the ground state phase diagram as a function of nonmagnetic impurity concentration p and bilayer coupling g. At the site percolation threshold, there exists a multicritical point at small but nonzero bilayer coupling g(m)=0.15(3). The magnetic properties of the single-layer material La(2)Cu(1-p)(Zn,Mg)(p)O4 near the percolation threshold appear to be controlled by the proximity to this new quantum critical point.
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: O P
authors.initials: OP
authors.lastname: Vajk
authors.forename: M
authors.initials: M
authors.lastname: Greven