Using a tunable quantum wire to measure the large out-of-plane spin splitting of quasi two-dimensional holes in a GaAs nanostructure

The out-of-plane g-factor g_perp for quasi-2D holes in a (100) GaAs heterostructure is studied using a variable width quantum wire. A direct measurement of the Zeeman splitting is performed in a magnetic field applied perpendicular to the 2D plane. We measure an out-of-plane g-factor up to g_perp = 5, which is larger than previous optical studies of g_perp, and is approaching the long predicted but never experimentally verified out-of-plane g-factor of 7.2 for heavy holes.