A Spin current without power reduction

1. Sep 1, 2016

hokhani

Spin current is defined as $I_s=I_\uparrow -I_\downarrow$ in which $I_\uparrow$ and $I_\downarrow$are the currents of spin up and down electrons respectively. One of the advantages of the spin current is that if $I_\uparrow =-I_\downarrow$, then the charge current $I_C=I_\uparrow +I_\downarrow=0$ while the spin current is not zero. Therefore, the spin is transferred without charge transfer (and so without power reduction as referred in some papers). Now, the question is raised that how the power reduction is zero while the two currents $I_\uparrow$ and $I_\downarrow$ independently waste the power?

2. Sep 6, 2016