Quantum spin hydrodynamics and a new spin-current mode in ferromagnetic   metals
  We derive the quantum spin hydrodynamic equations in a ferromagnetic metal.   From these equations we show the existence of a new massive spin-current mode. This mode can be observed in neutron scattering experiments and we discuss the difficulties in seeing it. At the end we discuss the existence of this mode in localized ferromagnets. 
Kevin S. Bedell and Krastan B. Blagoev