Spinning Electrons

Presented by Roland Winkler, Northern Illinois University and Argonne National Laboratory

Spin-orbit coupling makes the electron's spin degree of freedom respond to its orbital environment. Thus it gives us a "control knob" with which we can steer the purely quantum-mechanical spin degree of freedom. Recently, the electron's spin and spin-orbit coupling have attracted much attention due to the possibility to complement conventional charge-based electronics by novel approaches that use also the electron's spin ("spintronics"). In my talk I will provide a general introduction to the world of spinning electrons, followed by a discussion of a few examples of the rich and fascinating physics that emerges from the interplay between the spin and orbital dynamics of electrons in solids. Similar to an external magnetic field, spin-orbit coupling can give rise to an oscillatory motion of the spins known as spin precession. In my talk, I will show how the precessional spin dynamics plays a central role for several rather different phenomena. It can be used to generate a spin density (spin polarization) and a spin current (a flow of spin angular momentum even in the absence of a charge current). Furthermore, it can be used to manipulate spins. Finally, spin precession is also an important cause for the spin relaxation, i.e., the often unwanted yet unavoidable return to equilibrium of a nonequilibrium spin polarization imposed on an electron system.