<I>Review</I>/<I>Synthèse</I>: Triangular antiferromagnets

Abstract

In this article we review the effects of magnetic frustation in the stacked\ntriangular lattice. Frustration increases the degeneracy of the ground state,\ngiving rise to different physics. In particular it leads to unique phase\ndiagrams with multicritical points and novel critical phenomena. We describe\nthe confrontation of theory and experiment for a number of systems with\ndiffering magnetic Hamiltonians; Heisenberg, Heisenberg with easy-axis\nanisotropy, Heisenberg with easy-plane anisotropy, Ising and singlet ground\nstate. Interestingly each leads to different magnetic properties and phase\ndiagrams. We also describe the effects of ferromagnetic, rather than\nantiferromagnetic, stacking and of small distortions of the triangular lattice.\n