Beating patterns in the oscillatory magnetoresistance originatedfrom zero-field spin splitting in Al_xGa_1-xN/GaN heterostructures

Beating patterns in the oscillatory magnetoresistance in Al0.11 Ga0.89 NGaN heterostructures with one subband occupation have been investigated by means of temperature dependent Shubnikov-de Haas measurements at low temperatures and high magnetic fields. The zero-field spin splitting effect is observed by excluding the magnetointersubband scattering effect. The obtained zero-field spin splitting energy is 2.5 meV, and the obtained spin-orbit coupling parameter is 2.2× 10-12 eV m. Despite the strong polarization-induced electric field in the heterostructures, the spin-orbit coupling parameter in Alx Ga1-x NGaN heterostructures is smaller than that in other heterostructures, such as Inx Ga1-x As Iny Al1-y As ones. This is due to the large effective mass of the two-dimensional electron gas and the large GaN energy band gap in Alx Ga1-x NGaN heterostructures. With an increase in magnetic field, the spin splitting energy becomes smaller. The zero-field effect is still the dominant mechanism in Alx Ga1-x NGaN heterostructures at a magnetic field as high as 4.4 T.