Saturations fields in the Shubnikov-de Haas oscillations

We study the Shubnikov-de Haas oscillations in the magnetoresistance and Landauer conductance of a three strip quasi-2D semiconductor wave guide with thickness delta(z) and transversal width w(y). We assume that the strip in the middle, of length l(H), is subject to a homogeneous magnetic field, tilted by theta(H) with respect to the normal z of the 2DEG. The structure of the Shubnikov-de Haas oscillations, associated with spin parallel and antiparallel to the z-component of the magnetic field, and the finiteness of l(H), lead us to define, related with the limits between the corresponding Landau levels and the continuous spectrum, two characteristic saturation fields B-sat,up arrow = 2 Phi(o)/l(H)cos theta(H) (2n(S)/pi - 1/delta(2)(z))(1/2) and B-sat,down arrow defined by the positive root of B-sat(2),(down arrow) + 4g Phi(o)/pi l(H)(2)cos(2)theta(H) B-sat,(down arrow) - B-sat,(up arrow) = 0. Here g is the Lande factor, Phi(o) the unit magnetic flux and n(s) the charge concentration. We also obtain the polarization field B-p = Phi(o)/g 2n(s) - pi/delta(2)(z). (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.