Recent quasi-2D systems with judicious exploitation of the atomic monolayer or few-layer architecture exhibit unprecedented physical properties that challenge the conventional wisdom on the condensed matter physics. Here we show that the infinite layer SrCuO2 (SCO), a topical cuprate Mott insulator in the bulk form, can manifest an unexpected metallic state in the quasi-2D limit when SCO is grown on TiO2-terminated SrTiO3 (STO) substrates. Hard x-ray core-level photoemission spectra demonstrate a definitive Fermi level that resembles the hole doped metal. Soft x-ray absorption spectroscopy also reveals features analogous to those of a hole doped Mott insulator. Based on these results, we conclude that the hole doping does not occur at the interfaces between SCO and STO; instead, it comes from the transient layers between the chain type and the planar type structures within the SCO slab. The present work reveals a novel metallic state in the infinite layer SCO and invites further examination to elucidate the spatial extent of this state.
@article{arxiv.2212.07134,
title = {An emergent quasi-2D metallic state derived from the Mott insulator framework},
author = {P. -C. Chiang and S. C. Lin and C. -Y. Chiang and C. -S. Ku and S. W. Huang and J. M. Lee and Y. -D. Chuang and H. J. Lin and Y. F. Liao and C. -M. Cheng and S. C. Haw and J. M. Chen and Y. -H. Chu and T. H. Do and C. W. Luo and J. -Y. Juang and K. H. Wu and Y. -W. Chang and J. -C. Yang and J. -Y. Lin},
journal= {arXiv preprint arXiv:2212.07134},
year = {2023}
}