Proper definition of spin current in spin-orbit coupled systems

Phys Rev Lett. 2006 Feb 24;96(7):076604. doi: 10.1103/PhysRevLett.96.076604. Epub 2006 Feb 24.


The conventional definition of spin current is incomplete and unphysical in describing spin transport in systems with spin-orbit coupling. A proper and measurable spin current is established in this study, which fits well into the standard framework of near-equilibrium transport theory and has the desirable property to vanish in insulators with localized orbitals. Experimental implications of our theory are discussed.