Universal Critical Temperature for Kosterlitz-Thouless Transitions in Bilayer Quantum Magnets

Recent experiments show that double layer quantum Hall systems may have a ground state with canted antiferromagnetic order. In the vicinity of a quantum critical point, the order vanishes at a temperature TKT0ex0ex=0ex0exκH, where H is the magnetic field and κ is a universal number. We present quantum Monte Carlo simulations on a model spin system which support the universality of κ and determine its value. This allows experimental tests of an intrinsically quantum-mechanical universal quantity, which is not also a property of a higher dimensional classical critical point.