Finite-temperature ordering in two-dimensional magnets

Finite-temperature behavior of anisotropic two-sublattice magnets

Se p 20 06 Finite - temperature ordering in a two - dimensional highly frustrated spin model

We investigate the classical counterpart of an effective Hamiltonian for a strongly trimerized kagomé lattice. Although the Hamiltonian only has a discrete symmetry, the classical groundstate manifold has a continuous global rotational symmetry. Two cases should be distinguished for the sign of the exchange constant. In one case, the groundstate has a 120 • spin structure. To determine the tran...

Supersymmetric Two-dimensional Qcd at Finite Temperature *

Light-cone coordinates and supersymmetric discrete light-cone quantization are used to analyze the thermodynamics of two-dimensional supersymmetric quantum chromodynamics with a Chern–Simons term in the large-Nc approximation. This requires estimation of the entire spectrum of the theory, which is done with a new algorithm based on Lanczos iterations. Although this work is still in progress, so...

Magnetic Field Induced Ordering in Quasi-One-Dimensional Quantum Magnets

Three-dimensional magnetic ordering transitions are studied theoretically in strongly anisotropic quantum magnets. An external magnetic field can drive quasi-one-dimensional subsystems with a spin gap into a gapless regime, thus inducing long-range three-dimensional magnetic ordering due to weak residual magnetic coupling between the subsystems. Compounds with higher spin degrees of freedom, su...

Dynamics of Vortices in Two-Dimensional Magnets

Theories, simulations and experiments on vortex dynamics in quasi-two-dimensional magnetic materials are reviewed. These materials can be modelled by the classical two-dimensional anisotropic Heisenberg model with XY (easy-plane) symmetry. There are two types of vortices, characterized by their polarization (a second topological charge in addition to the vorticity): Planar vortices have Newtoni...