Electrical properties and subband occupancy at the (La, Sr)(Al, Ta)O3/SrTiO3 interface

• Main Authors: Han, K., Huang, Z., Zeng, S. W., Yang, M., Li, C. J., Zhou, W. X., Wang, Renshaw Xiao, Venkatesan, T., Coey, J. M. D., Goiran, M., Escoffier, W., Ariando
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2019
• Subjects: Electronic Structure; Hall Effect; DRNTU::Science::Physics
• Online Access: https://hdl.handle.net/10356/106772; http://hdl.handle.net/10220/48973
• Institution: Nanyang Technological University

The quasi-two-dimensional electron gas at oxide interfaces provides a platform for investigating quantum phenomena in strongly correlated electronic systems. Here, we study the transport properties at the high-mobility (La0.3Sr0.7) (Al0.65Ta0.35) O3/SrTiO3 interface. Before oxygen annealing, the as-grown interface exhibits a high electron density and electron occupancy of two subbands: higher-mobility electrons (μ1≈10^4 cm2 V−1s−1 at 2 K) occupy the lower-energy 3dxy subband, while lower-mobility electrons (μ1≈103cm2V−1s−1 at 2 K) propagate in the higher-energy 3dxz/yz-dominated subband. After removing oxygen vacancies by annealing in oxygen, only a single type of 3dxy electrons remain at the annealed interface, showing tunable Shubnikov–de Haas oscillations below 9 T at 2 K and an effective mass of 0.7me. By contrast, no oscillation is observed at the as-grown interface even when electron mobility is increased to 50 000 cm2V−1s−1 by gating voltage. Our results reveal the important roles of both carrier mobility and subband occupancy in tuning the quantum transport at oxide interfaces.