The quantum Heisenberg antiferromagnet on the square lattice

The Heisenberg antiferromagnet on the square-kagomé lattice

We discuss the ground state, the low-lying excitations as well as high-field thermodynamics of the Heisenberg antiferromagnet on the two-dimensional square-kagomé lattice. This magnetic system belongs to the class of highly frustrated spin systems with an infinite non-trivial degeneracy of the classical ground state as it is also known for the Heisenberg antiferromagnet on the kagomé and on the...

Comment on "quantum phase transition of the randomly diluted Heisenberg antiferromagnet on a square lattice".

Ground-state magnetic properties of the diluted Heisenberg antiferromagnet on a square lattice are investigated by means of the quantum Monte Carlo method with the continuous-time loop algorithm. It is found that the critical concentration of magnetic sites is independent of the spin size S, and equal to the two-dimensional percolation threshold. However, the existence of quantum fluctuations m...

Chern-Simons theory of the anisotropic quantum Heisenberg antiferromagnet on a square lattice.

We consider the anisotropic quantum Heisenberg antiferromagnet (with anisotropy λ) on a square lattice using a Chern-Simons (or Wigner-Jordan) approach. We show that the Average Field Approximation (AFA) yields a phase diagram with two phases: a Neèl state for λ > λc and a flux phase for λ < λc separated by a second order transition at λc < 1. We show that this phase diagram does not describe t...

Heisenberg Antiferromagnet on Square-Kagomé Lattice: Resonating Valence Bond Description

Modified Spin Wave Thoery of the Bilayer Square Lattice Frustrated Quantum Heisenberg Antiferromagnet

The ground state of the square lattice bilayer quantum antiferromagnet with nearest and next-nearest neighbour intralayer interaction is studied by means of the modified spin wave method. For weak interlayer coupling, the ground state is found to be always magnetically ordered while the quantum disordered phase appear for large enough interlayer coupling. The properties of the disordered phase ...