Spiral phase of a doped quantum antiferromagnet

Abstract
A low density of vacancies in a 2D, spin-(1/2, Heisenberg antiferromagnet leads (for a range of effective couplings) to a metallic phase with incommensurate antiferromagnetic order, i.e., with the staggered magnetization rotating in a plane with the wave number proportional to the density. This structure originates from the polarization of the antiferromagnetic dipole moments of the vacancies. The excitation spectrum of this spiral state includes an interesting low-lying mode. Implications for neutron scattering and normal-state resistivity are discussed.