Gate-defined Quantum Point Contact in an InSb Two-dimensional Electron Gas

We investigate an electrostatically defined quantum point contact in a high-mobility InSb two-dimensional electron gas. Well-defined conductance plateaus are observed, and the subband structure of the quantum point contact is extracted from finite-bias measurements. The Zeeman splitting is measured in both in-plane and out-of-plane magnetic fields. We find an in-plane g factor $|g_{parallel}^* | approx$ 40. The out-of-plane g factor is measured to be $|g_{perp}^* | approx$ 50, which is close to the g factor in the bulk.