Spin-polarized two-dimensional electron gas in undoped MgxZn1−xO/ZnO heterostructures

Quantum transport properties of two-dimensional electron gas(2DEG) in undoped MgₓZn₁ˍₓO/ZnO heterostructures grown by metal organic vapor phase epitaxy have been investigated. A large zero-field spin-splitting energy more than 15 meV in the 2DEG is determined at 1.6 K. Meanwhile, ferromagnetism is observed in the heterostructures. The findings reveal that the 2DEG is spin polarized at zero magnetic fields. It is believed that the exchange interaction between the itinerant electrons in the two-dimensional channel and the magnetic polarons in the MgₓZn₁ˍₓO barrier around the interface results in the spin polarization of the 2DEG.This work was supported by National Basic Research Program of China (Nos. 2012CB921304 and 2012CB619306), the National Natural Science Foundation of China (Nos. 60806042, 11174008, and 60990313), the Research Fund for the Doctoral Program of Higher Education in China (200800011021), the Wuhan National High Magnetic Field Center (WHMFCKF2011004), Singapore Agency for Science, Technology and Research (A*STAR) (No. 052- 126-0095) and Infuse Project No. I01-0911-06