Order-disorder transition in a two-layer quantum antiferromagnet

We have studied the antiferromagnetic order-disorder transition occurring at T=0 in a two-layer quantum Heisenberg antiferromagnet as the interplane coupling is increased. Finite-size scaling of quantum Monte Carlo results for the staggered structure factor gives the critical ratio J_c=2.51±0.02 between the interplane and in-plane coupling constants. The critical behavior is consistent with the 3D classical Heisenberg universality class. Results for the uniform magnetic susceptibility and the correlation length at finite temperature are compared with recent predictions for the (2+1)-dimensional nonlinear σ model.