Influence of magnetic field orientation on the Zeeman spin-splitting in InGaAs quantum point contacts

We present measurements of the Zeeman spin-splitting in a quantum point contact (QPC) etched into an InGaAs/InP heterostructure [1], comparing magnetic field orientations in the plane and perpendicular to the InGaAs quantum well. We observe an isotropic Zeeman splitting for fields oriented in the plane of the quantum well, with a magnitude that is enhanced by up to a factor of two compared to two-dimensional electron systems in InGaAs/InP [2]. The Zeeman splitting is much larger when the magnetic field is perpendicular to the quantum well, resulting in a g-factor of 15.7 in the one dimensional limit. \\[4pt] [1] T. P. Martin, \emph{et al.}, \emph{Appl. Phys. Lett.} \textbf{93}, 012105 (2008).\\[0pt] [2] B. Kowalski, \emph{et al.}, \emph{Phys. Rev. B} \textbf{49}, 14786 (1994).