Spin precession and modulation in ballistic cylindrical nanowires due to the Rashba effect

The spin precession in a cylindrical semiconductor nanowire due to Rashba spin-orbit coupling has been investigated theoretically using an InAs nanowire containing a surface two-dimensional electron gas as a model. The eigenstates, energy-momentum dispersion, and the energy-magnetic field dispersion relation are determined by solving the Schrodinger equation in a cylindrical symmetry. The combination of states with the same total angular momentum but opposite spin orientation results in a periodic modulation of the axial spin component along the axis of the wire. Spin-precession about the wires axis is achieved by interference of two states with different total angular momentum. Because a superposition state with exact opposite spin precession exists at zero magnetic field, an oscillation of the spin orientation can be obtained. If an axially oriented magnetic field is applied, the spin gains an additional precessing component.