Electronic phase separation (EPS) originates from an incomplete transformation between electronic phases, causing the inhomogeneous spatial distribution of electronic properties. In the system of two-dimensional electron gas (2DEG), the EPS is usually identified based on a percolative metal-to-superconductor transition. Here, we report a metal-insulator transition (MIT) in KTaO3-based 2DEG with the width of conductive channel decreasing into micrometer scale. Hysteretic resistance-temperature relations are observed due to the competition between metallic and insulating phases, which is tunable by magnetic field. Such a size-dependent MIT effect is attributed to the coexistence and separation of metallic and insulating phases. Combining density functional theory calculation, we propose a theoretical model to simulate the dynamic process of the EPS using the percolation theory, demonstrating the mechanism of size-dependent MIT. Our work suggests a clear and simple 2DEG platform to achieve the spatial coexistence of metallic and insulating phases.
@article{arxiv.2211.14464,
title = {Metal-insulator phase separation in KTaO3-based two-dimensional electron gas},
author = {Jinlei Zhang and Jiayong Zhang and Dapeng Cui and Li Ye and Shuainan Gong and Zhichao Wang and Zhenping Wu and Chunlan Ma and Ju Gao and Yuanyuan Zhao and Yucheng Jiang},
journal= {arXiv preprint arXiv:2211.14464},
year = {2022}
}