Multiple subband crossing in a one-dimensional hole gas with enhanced g-factors

Abstract

We have measured the transport properties of one-dimensional ballistic constrictions defined in a two-dimensional hole gas. The conductance quantization of the constrictions switches between even and odd multiples of e 2/ h as a function of a parallel magnetic field, as spin-splitting causes the subbands of the 1D channel to cross repeatedly. The in-plane g-factors of the 1D subbands are measured from the low field data. We find them to increase as the number of occupied 1D subbands decreases and attribute this enhancement of the g-factor to Coulomb interactions. The quantization at high fields shows that the subbands have crossed four times; in this regime the system is highly magnetized and exchange effects should be of particular importance.