title: Enhanced anisotropic effective g factors of an Al0.25Ga0.75N/GaN heterostructure based quantum point contact.
abstract: Gate-defined quantum point contacts (QPCs) were fabricated with Al0.25Ga0.75N/GaN heterostructures grown by metal-organic chemical vapor deposition (MOCVD). In the transport study of the Zeeman effect, greatly enhanced effective g factors (g*) were obtained. The in-plane g* is found to be 5.5 ± 0.6, 4.8 ± 0.4, and 4.2 ± 0.4 for the first to the third subband, respectively. Similarly, the out-of-plane g* is 8.3 ± 0.6, 6.7 ± 0.7, and 5.1 ± 0.7. Increasing g* with the population of odd-numbered spin-splitted subbands are obtained at 14 T. This portion of increase is assumed to arise from the exchange interaction in one-dimensional systems. A careful analysis shows that not only the exchange interaction but the spin-orbit interaction (SOI) in the strongly confined QPC contributes to the enhancement and anisotropy of g* in different subbands. An approach to distinguish the respective contributions from the SOI and exchange interaction is therefore proposed.
authors.affiliation: State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University , Beijing 100871, People's Republic of China.
authors.forename: Fangchao
authors.initials: F
authors.lastname: Lu
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.forename: Shaoyun
authors.initials: S
authors.lastname: Huang
authors.forename: Marcus
authors.initials: M
authors.lastname: Larsson
authors.forename: Ivan
authors.initials: I
authors.lastname: Maximov
authors.forename: Mariusz
authors.initials: M
authors.lastname: Graczyk
authors.forename: Junxi
authors.initials: J
authors.lastname: Duan
authors.forename: Sidong
authors.initials: S
authors.lastname: Liu
authors.forename: Weikun
authors.initials: W
authors.lastname: Ge
authors.forename: Fujun
authors.initials: F
authors.lastname: Xu
authors.forename: Bo
authors.initials: B
authors.lastname: Shen