Universal quantum-critical dynamics of two-dimensional antiferromagnets.

The universal dynamic and static properties of two dimensional antiferromagnets in the vicinity of a zero-temperature phase transition from long-range magnetic order to a quantum disordered phase are studied. Random antiferromagnets with both Néel and spin-glass longrange magnetic order are considered. Explicit quantum-critical dynamic scaling functions are computed in a 1/N expansion to two-loops for certain non-random, frustrated square lattice antiferromagnets. Implications for neutron scattering experiments on the doped cuprates are noted.