Magnetotransport of electrically induced two-dimensional hole gases in undoped GaSb quantum wells

We have performed magnetotransport measurements on electrically induced two-dimensional hole gases in undoped GaSb/AlSb quantum wells. The mobilities of the holes are sufficient to observe Shubnikov-de Haas oscillations for a few teslas of perpendicular magnetic field. We extracted the effective masses of holes in the valence bands from temperature-dependent Shubnikov-de Haas oscillations. The effective masses, in the unit of the free-electron mass, strongly depend on the width of the quantum wells and are 0.14-0.16 for the spin-degenerated subbands in an 8-nm-thick quantum well and 0.44-0.52 for one of the spin-split subbands in a 25-nm-thick quantum well. Furthermore, by fitting the weak antilocalization correction to the classical magnetoresistance at low magnetic fields, we obtained the phase coherence length of the system. The phase coherence length increases with hole density, reaching maxima of around 1100 and 600 nm for the 8- A nd 25-nm-thick quantum wells, respectively. These achievements build upon our previous results on GaSb quantum wells and further our understanding of their properties. They therefore lay the groundwork for realizing spin-based electronics based on the strong spin-orbit interaction in this promising system.