is the four-terminal longitudinal r

is the four-terminal longitudinal resistance of point contact i. Equation (3.39) predicts a nonmonotonic Bdependence for Gseries. This can most easily be seen by disregarding the discreteness of N and Nwide. We then have NL ≈ EF/ˉhωc, while the magnetic field dependence of N (for a square-well confining potential in the point contacts) is given by Eq. (2.62). The resulting B-dependence of Gseries is shown in Fig. 64 (dotted curves). The nonmonotonic behavior is due to the delayed depopulation of subbands in the point contacts compared with the broad 2DEG. While the number of occupied Landau levels Nwide in the region between the point contacts decreases steadily with B for 2lcycl < L, the number N of occupied subbands in the point contacts remains approximately constant until 2lc,min ≈ Wmin, with lc,min ≡ lcycl(1 . Ec/EF)1/2 denoting the cyclotron radius in the point contact region. In this field interval Gseries increases with B, according to Eq. (3.39). For stronger fields, depopulation in the point contacts begins to dominate Gseries, leading finally to a decreasing conductance (as is the rule for single point contacts; see Section III.B.2). The peak in Gseries thus occurs at 2lc,min ≈ Wmin.