Spinors, Spin Coefficients and Lanczos Potentials
  It has been demonstrated, in a number of special situations, that the spin coefficients of a canonical spinor dyad can be used to define a Lanczos potential of the Weyl curvature spinor. In this paper we explore some of these potentials and show that they can be defined directly from the spinor dyad in a very simple way, but that the results do not generalize significantly, in any direct manner. A link to metric, asymmetric, curvature-free connections, which suggests a more natural relationship between the Lanczos potential and spin coefficients, is also considered. 
F. Andersson and S. B. Edgar