  We show that spin anisotropy can be transferred to an isotropic system by
transport of spin quadrupole moment. We derive the quadrupole moment current
and continuity equation and study a high-spin valve structure consisting of two
ferromagnets coupled to a quantum dot probing an impurity spin. The quadrupole
back-action on their coupled spin results in spin torques and anisotropic spin
relaxation which do not follow from standard spin current considerations. We
demonstrate the detection of the impurity spin by charge transport and its
manipulation by electric fields.
