Hydrodynamics of an antiferromagnet with fermions.

Abstract

The long-wavelength description of a doped two-dimensional antiferromagnet (AFM) is considered. By assuming the existence of local AFM correlations, the hydrodynamics of the AFM and fermionic degrees of freedom is given. The broken time-reversal symmetry in the AFM leads to the spinor nature of doped fermions, and we find that the total ``pseudospin'' of fermions is conserved. This leads to the existence of additional hydrodynamic diffusive modes. This pseudospin index leads to possible ``singlet'' and ``triplet'' superconducting condensates in magnetically correlated materials. At low temperatures we find nonhydrodynamic damping of spin waves due to scattering by fermions.