Influence of the illumination on the beating patterns in the oscillatory magnetoresistance in Alx Ga1-x NGaN heterostructures

The beating patterns in the oscillatory magnetoresistance originating from zero-field spin-splitting and magnetointersubband scattering (MIS) effects of the two-dimensional electron gas (2DEG) in Alx Ga1-x NGaN heterostructures have been investigated by means of magnetotransport measurements under illumination. It is observed that the energy separation between the two subbands decreases due to the weakened electric field at the Alx Ga1-x NGaN heterointerfaces after the illumination. Meanwhile, the beating nodes induced by the MIS effect shift to higher magnetic field due to the increase of the 2DEG concentration at the second subband, and the beating nodes induced by the zero-field spin-splitting effect shift to lower magnetic field due to the decrease of the spin-splitting energy of the 2DEG. Since the weakened electric field decreases the zero-field spin-splitting energy, it is suggested that the zero-field spin splitting of the 2DEG in Alx Ga1-x NGaN heterostructures mainly arises from the Rashba effect.