The In-Plane Anisotropy Of The Effective G Factors In Al0.25ga0.75n/Gan Based Quantum Point Contacts With Narrow Channels

The effective g factors (g*) of the lowest three subbands of Al0.25Ga0.75N/GaN-based quantum point contacts (QPCs) are obtained in various magnetic field orientations. The g factors show an anisotropic enhancement compared to those in the two-dimensional electron gas, among which an in-plane anisotropy becomes manifested, when the QPC is depleted from the third to the first subband and the channel width shrinks from the order of 10(-7) m-10(-8) m. In the one-dimensional (1D) regime with only one subband in the QPC, the in-plane g* perpendicular to the current is evidently larger than the parallel one. The in-plane anisotropy can be attributed to the Rashba spin-orbit coupling (SOC) in the narrow confinement. The reason that the anisotropy can be observed in this work, but not in conventional III-V semiconductors studied previously, is due to the fact that the Al0.25Ga0.75N/GaN-based QPCs have larger polarization-field-induced Rashba SOC and much stronger 1D constriction.