Effects of Rashba spin-orbit coupling and a magnetic field on a   polygonal quantum ring
  Using standard quantum network method, we analytically investigate the effect of Rashba spin-orbit coupling (RSOC) and a magnetic field on the spin transport properties of a polygonal quantum ring. Using Landauer-Buttiker formula, we have found that the polarization direction and phase of transmitted electrons can be controlled by both the magnetic field and RSOC. A device to generate a spin-polarized conductance in a polygon with an arbitrary number of sides is discussed. This device would permit precise control of spin and selectively provide spin filtering for either spin up or spin down simply by interchanging the source and drain. 
Han-Zhao Tang, Li-Xue Zhai, Man Shen, Jian-Jun Liu
cond-mat.mes-hall