One of the central questions in cuprate superconductivity is if superconductivity can exist in an isolated single CuO2 plane without any interlayer coupling. There have been numerous experimental efforts to answer this question, but it still has not been clearly resolved. Here we present a heterostructure system with an isolated half-unit-cell La2−xSrxCuO4 which has a single CuO2 plane. Using in-situ angle-resolved photoemission spectroscopy, we measured the electronic and gap structures of a single CuO2 plane. We observed a \textit{d}-wave-like gap which closes somewhat above the bulk Tc. Moreover, almost identical gap properties are seen for both single CuO2 plane and bulk. These observations lead us to the conclusion that the d-wave superconductivity of cuprates also exists in a single CuO2 plane. Our results demonstrate that cuprate superconductivity is essentially a two-dimensional phenomenon and provide a platform to study cuprate superconductivity in a purely two-dimensional system.
@article{arxiv.2602.06389,
title = {Superconductivity in Isolated Single Copper Oxygen Plane},
author = {Youngdo Kim and Byeongjun Gil and Sehoon Kim and Yeonjae Lee and Donghan Kim and Jaeung Lee and Jinyoung Kim and Younsik Kim and Miyoung Kim and Changyoung Kim},
journal= {arXiv preprint arXiv:2602.06389},
year = {2026}
}