Strong enhancement of g-factor in PbTe-Pb hybrid nanowires

Abstract

We report large Lande g-factors observed in PbTe-Pb hybrid nanowires. The g-factor can reach 83, significantly larger than those in bare PbTe nanowires (typically below 20). We attribute this enhancement to orbital effects in the superconducting film, particularly when the magnetic field is nearly perpendicular to the Pb film. This enhancement is beneficial for the search for topological superconductivity by reducing the critical magnetic field required for the phase transition.

Figures (4)

• Figure 1: Device set up. (a) SEM of device A. Scale bar is 1 micron. Source and drain contacts are denoted as S and D, respectively. (b) Schematic of the device. The Al$_2$O$_3$ dielectric is in green (labeled as AlO). (c) 3D illustration of the coordinate axes.
• Figure 2: (a) $G$ as a function of $V$ and $B$. $B$ is aligned with the $y$ axis as shown in (b). The cyan and pink dashed lines are linear fits of the subgap state dispersion. (c) $B$ scan by orienting $B$ at $\theta$ = 90$^{\circ}$, $\phi$ = 110$^{\circ}$, i.e. 20$^{\circ}$ away from the $y$ axis. The color bar is identical to that in (a). For (a) and (c), $V_{\text{TG}}$ = -3.57 V, $V_{\text{SG}}$ = -3.496 V. (d) Replot of (c) by normalizing the conductance at each $B$. (e) Waterfall plot of (c), shown in two panels (for clarity). The vertical offsets are 0.07 (lower panel) and 0.02 (upper panel) in the unit of $2e^2/h$. The red curves are ZBPs.
• Figure 3: (a) $B$ scans along different orientations in the $xy$ plane. $\theta$ = 90$^{\circ}$. From left to right, $\phi$ = 0$^\circ$, 30$^\circ$, 55$^\circ$, 75$^\circ$, 90$^\circ$, respectively. $V_{\text{TG}}$ = -3.714 V for the 0$^{\circ}$ and 90$^{\circ}$ cases, and -3.73 V for other panels. $V_{\text{SG}}$ = -3.456 V for the 0$^{\circ}$ case, -3.444 V for the 90$^{\circ}$ case, and -3.48 V for the rest panels. (b) Schematic of these orientations, indicated by the arrows. (c) $B$ scan along the nanowire axis (the $z$ axis). The color bar is identical to that in (a). $V_{\text{TG}}$ = -3.714 V, $V_{\text{SG}}$ = -3.456 V. (d-f) Rotating $B$ in $xy$, $yz$, and $xz$ planes, respectively. $|B|$ is fixed at 0.19 T. Upper panels are the schematics of the rotating planes. $V_{\text{TG}}$ = -3.57 V, $V_{\text{SG}}$ = -3.496 V. The minor adjustments in gate voltages are to compensate for the gate drift between scans.
• Figure 4: (a) $B$ scan at $V_{\text{TG}}$ = -3.714 V, $V_{\text{SG}}$ = -3.4631 V. $\theta$ = 90$^{\circ}$, $\phi$ = 110$^{\circ}$. Lower panel, zero-bias line cut. (b) A line cut from (a) at 0.2 T. (c-d) $B$ rotation by fixing $\phi$ = 110$^{\circ}$ and rotating $\theta$. The rotating plane is sketched in (c). Lower panel of (d) shows the zero-bias line cut. (e) $V_{\text{TG}}$ scan at zero field. $V_{\text{SG}}$ = -3.4631 V. (f) $V_{\text{TG}}$ scan at 0.19 T ($\theta$ = 90$^{\circ}$, $\phi$ = 110$^{\circ}$). $V_{\text{SG}}$ = -3.44 V. Lower panel, zero-bias line cut.