Quantum Monte Carlo Study of Inhomogeneous Bond Dilution in the Two-Dimensional Heisenberg Antiferromagnet

The problem whether a two-dimensional Heisenberg antiferromagnet on a square lattice can be driven through a quantum phase transition by either bond or site dilution has attracted a lot of recent interest. Such a diluted system is of direct relevance for antiferromagnetic layered cuprates compounds, doped with nonmagnetic impurities. Both experimental results and numerical analysis now give evidence that such systems with homogeneous site and bond dilution are driven through a classical percolation transition instead of a quantum phase transition. In this paper we show that inhomogeneous bond dilution introduces the different scenario of a percolative quantum phase transition. The ground state of the bond-diluted system can be a spin liquid characterized by an infinite percolating network with vanishing antiferromagnetic order parameter. This quantum disordered phase appears as an intermediate regime between the geometrically disordered phase and the antiferromagnetic ordered phase. Here we investigate this phenomenon using Stochastic Series Expansion Quantum Monte Carlo simulations.