Two-Dimensional Superconductivity at the CaZrO3/KTaO3 (001) Heterointerfaces

Lu Chen; Siyi Zhou; Daming Tian; Yinan Xiao; Qixuan Gao; Yongchao Wang; Yuansha Chen; Fengxia Hu; Baogen Shen; Jirong Sun; Weisheng Zhao; Jinsong Zhang; Hui Zhang

arXiv · 2507.01392

Two-Dimensional Superconductivity at the CaZrO3/KTaO3 (001) Heterointerfaces

Lu Chen·Siyi Zhou·Daming Tian·Yinan Xiao·Qixuan Gao·Yongchao Wang·Yuansha Chen·Fengxia Hu·Baogen Shen·Jirong Sun·Weisheng Zhao·Jinsong Zhang·Hui Zhang

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Abstract

Two-dimensional superconductivity at KTaO3 (KTO) heterointerfaces has sparked intensive investigations since its discovery, yet whether the (001)-oriented KTO interface hosts superconductivity remains to be elucidated. Here, we provide unambiguous evidence of superconductivity in two-dimensional electron gases (2DEGs) at CaZrO3/KTO(001) heterointerfaces, with a superconducting transition TC up to ~0.25 K. Notably, TC increases linearly with carrier density nS over the range of 4.5*10^13~10.3*10^13 cm^-2. Furthermore, superconductivity exhibits a pronounced dependence on crystallographic orientation, with TC rising from 0.25 K for (001) to 1.04 K for (110) and 2.22 K for (111), underscoring the crucial role of interfacial symmetry in the CaZrO3/KTO system. The two-dimensional nature of the superconducting state is corroborated by the Berezinskii-Kosterlitz-Thouless (BKT) transition and the large anisotropy of the upper critical field. For the CaZrO3/KTO(001) sample with nS=7.7*10^13 cm^-2, the estimated Ginzburg-Landau coherence length {\xi}GL=146.4 nm is larger than the superconducting layer thickness dSC=10.1 nm by a factor of ~14.5, confirming significant two-dimensional confinement of the CaZrO3/KTO(001) superconductor. In addition, we demonstrate that the two-dimensional superconductivity at the CaZrO3/KTO(001) interface can be effectively tuned by applying a back gate voltage. Our findings reveal the existence of two-dimensional superconductivity at CaZrO3/KTO(001), providing a new platform for exploring two-dimensional superconductivity at oxide interfaces.

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Lu Chen, Siyi Zhou, Daming Tian, Yinan Xiao, Qixuan Gao, Yongchao Wang, Yuansha Chen, Fengxia Hu, Baogen Shen, Jirong Sun, Weisheng Zhao, Jinsong Zhang, Hui Zhang. 2025-07-02. Two-Dimensional Superconductivity at the CaZrO3/KTaO3 (001) Heterointerfaces. https://arxiv.org/abs/2507.01392

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