Bilayer Heisenberg quantum antiferromagnet

A (single-layer) two-dimensional Heisenberg quantum antiferromagnet consists of quantum spins- on the sites of a square lattice. They interact via the Hamiltonian 

The Hamiltonian of the resulting bilayer Heisenberg quantum antiferromagnet reads 

We now map this quantum phase transition onto a classical transition. Chakravarty and co-workers ° showed that the low-energy behavior of two-dimensional quantum Heisenberg antiferromagnets is generally described by a (2 - - l)-dimensional quantum rotor model with the Euclidean action 

Here the value of K is determined by the ratio J /Jx and tunes the phase transition. (Since the interaction is short ranged in space and time directions, the anisotropy of Eq. [21] does not play a role in the critical behavior.) 

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The simplest case is when the parameter A multiplies all terms on a subset of the bonds. An example is the bilayer Heisenberg quantum antiferromagnet with Hamiltonian... 

Figure 4 Sketch of the bilayer Heisenberg quantum antiferromagnet. Each lattice site is occupied by a quantum spin-J,...

Table 3 Critical Exponents of the Generic Transition, Percolation Transition, and Multicritical Point of the Dimer-Diluted Bilayer Quantum Heisenberg Antiferromagnet...

Gonventional Scaling and Universality in a Disordered Bilayer Quantum Heisenberg Antiferromagnet. 

Finite-Size Scaling Analysis of the Quantum Critical Point of S = 1/2 Heisenberg Antiferromagnetic Bilayers. 

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