Magnetic properties of frustrated two-dimensional S=1/2 antiferromagnets on a square lattice

An overview on the basic magnetic properties of vanadates which
represent prototypes of frustrated two-dimensional S=1/2 antiferromagnets on a square lattice is presented. It will be shown how information on the ground state sublattice magnetization on the static uniform susceptibility and on the frustration driven lattice distortions can be achieved by means of NMR spectroscopy and magnetization measurements. The low-energy spin excitations investigated by means of NMR and muSR relaxation measurements will be analyzed and the anomalous
very-low-frequency dynamics originating from the degeneracy of the ground state discussed. Finally the effects of an hydrostatic pressure on the degree of frustration of the vanadates will be addressed.