Magnetocapacitance of quantum wires: Effect of confining potential on one-dimensional subbands and suppression of exchange enhanced g factor

By means of magnetocapacitance measurements, we study subband filling in field effect induced arrays of quantum wires in GaAs/AlGaAs heterostructures. The confining potential is defined by fork-shaped interdigitated metallic gates with lithographic width of $\sim 150\hspace{0.5em}\mathrm{nm},$ realized by e-beam lithography. The capacitance allows us to investigate the density of states. Evolution of one-dimensional subband spacing and filling as a function of confinement, gate voltage and magnetic field is analyzed and quantitatively explained. Also the development of a structure related to spin splitting is studied as a function of both magnetic field and confinement. In different regimes, we find for the g factor either an enhancement up to a factor of almost 50 with respect to the “bare” value or a suppression, accounting for exchange interactions and kinetic energy of edge electrons, respectively, in agreement with theoretical models.