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Enhanced circular photogalvanic effect in oxide two-dimensional electron gas via photoelectric synergistic modulation

XiangYang Wei, ShuanHu Wang*, and KeXin Jin†

  • Shaanxi Key Laboratory of Condensed Matter Structures and Properties & MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

  • *Contact author: shwang2015@nwpu.edu.cn
  • †Contact author: jinkx@nwpu.edu.cn
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Phys. Rev. Research 8, 013258 – Published 9 March, 2026

DOI: https://doi.org/10.1103/t5rg-296w

Abstract

We report a giant enhancement of circular photogalvanic effect (CPGE) in the oxide two-dimensional electron gas at LaAlO3/SrTiO3 and LaAlO3/KTaO3 interfaces through the synergistic ultraviolet (UV) photoexcitation and electrostatic gating. The UV illumination generates high-density photocarriers by promoting valence-to-conduction band transitions, which simultaneously increase the Fermi wave vector kF and Fermi energy EF. Concurrently, the gate-induced oxygen vacancy migration toward the interface amplifies the Rashba spin-orbit coupling coefficient αR. Strikingly, the CPGE photocurrent exhibits a nonmonotonic dependence on both gate voltage and UV intensity, peaking at an optimal carrier density where kF and αR cooperatively enhance the spin-momentum locking. This dual control strategy achieves a CPGE responsivity of 22.71 µV for LaAlO3/KTaO3 interfaces. Our findings establish the photoelectric coupling as a powerful knob for tailoring nonequilibrium spin phenomena in quantum oxide interfaces, with direct implications for reconfigurable spintronic devices.

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Phys. Rev. Research 8, 013258– Published 9 March, 2026
  • Received 29 August 2025
  • Accepted 4 February 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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