Atomic-Layer Engineering of La2-xSrxCuO4-La2-xSrxZnO4 Heterostructures

Xiaotao Xu; Xi He; Anthony T Bollinger; Xiaoyan Shi; Ivan Božović

doi:10.3390/nano13152207

Atomic-Layer Engineering of La_2-xSr_xCuO₄-La_2-xSr_xZnO₄ Heterostructures

Nanomaterials (Basel). 2023 Jul 29;13(15):2207. doi: 10.3390/nano13152207.

Authors

Xiaotao Xu^{1

2}, Xi He^{1

3

4}, Anthony T Bollinger¹, Xiaoyan Shi², Ivan Božović^{1

3

4}

Affiliations

¹ Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA.
² Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA.
³ Department of Chemistry, Yale University, New Haven, CT 06520, USA.
⁴ Energy Sciences Institute, Yale University, West Haven, CT 06516, USA.

Abstract

The fabrication of trilayer superconductor-insulator-superconductor (SIS) Josephson junctions with high-temperature superconductor (HTS) electrodes requires atomically perfect interfaces. Therefore, despite great interest and efforts, this remained a challenge for over three decades. Here, we report the discovery of a new family of metastable materials, La_2-xSr_xZnO₄ (LSZO), synthesized by atomic-layer-by-layer molecular beam epitaxy (ALL-MBE). We show that LSZO is insulating and epitaxially compatible with an HTS compound, La_2-xSr_xCuO₄ (LSCO). Since the "parent" compound La₂ZnO₄ (LZO) is easier to grow, here we focus on this material as our insulating layer. Growing LZO at very low temperatures to reduce cation interdiffusion makes LSCO/LZO interfaces atomically sharp. We show that in LSCO/LZO/LSCO trilayers, the superconducting properties of the LSCO electrodes remain undiminished, unlike in previous attempts with insulator barriers made of other materials. This opens prospects to produce high-quality HTS tunnel junctions.

Keywords: cuprates; nanoengineering; oxide molecular beam epitaxy; superconductivity.

Abstract

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