Fig. 2
From: Ballistic superconductivity and tunable π–junctions in InSb quantum wells
Magnetic field-driven 0−π transitions. a Variation of the switching current, Is, with in-plane magnetic field, By, at Vg = 0 V for the same JJ as in Fig. 1b, c. Two distinct revivals of Is are visible at By = 470 mT and 1250 mT, associated with 0−π transitions. The data are from two cool downs (CDs). The momentum shift, δk/2, of the Fermi surfaces due to the Zeeman field is sketched in the inset. The solid (dashed) lines depict the situation at zero (finite) magnetic field, and the arrows represent the spin orientation. b Is as a function of By at Vg = 0 V for four JJs with different lengths. For better visibility, Is is normalized with respect to Is at By = 0 T. Dashed lines indicate B0-π, the field at which the transition occcurs for each length. The inset shows a linear dependence of B0-π on 1/L, in agreement with ballistic transport. c Is vs. By at three different Vg for the JJ with L = 1.1 μm. B0-π shifts to lower values of By with more negative gate voltages. Is vs. Vg at By = 400 mT shows a non-monotonic behavior as displayed in the inset. The length and gate dependence of panel b, c are in qualitative agreement with Eq. (1)
