Atomically-resolved interlayer charge ordering and its interplay with superconductivity in YBa₂Cu₃O₆.₈₁
Chun-Chih Hsu1, Bo-Chao Huang2, Michael Schnedler3, Ming-Yu Lai2, Yuh-Lin Wang1,2, Rafal E. Dunin-Borkowski3, Chia-Seng Chang4, Ting-Kuo Lee5, Philipp Ebert3, Ya-Ping Chiu1,4,6*
1Department of Physics, National Taiwan University, Taipei, Taiwan
2Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
3Peter Grünberg Institut, Forschungszentrum Jülich GmbH, Jülich, Germany
4Institute of Physics, Academia Sinica, Taipei, Taiwan
5Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
6Center of Atomic Initiative for New Materials, National Taiwan University, Taipei, Taiwan
* Presenter:Ya-Ping Chiu,
Charge order (CO) has been recognized as one of the most important competing order in superconductive cuprates. However, the most fundamental physical mechanisms governing CO, for example, the role of so-called charge reservoir (Cu-O chain) layers in CO and the spatial interplay of CO and SC, in highly-doped YBCO are still unclear.
Here, we present the direct real-space cross-sectional scanning tunneling microscopy (XSTM) imaging with atomic resolution to characterize the atomically resolved electronic structure along the c [001] direction in high-temperature superconductive YBa₂Cu₃O₆.₈₁ cuprates. We demonstrate that CO occurs on CuO plane and chain layers with an antiphase correlation along the c-axis direction governed by Coulomb repulsion rather than Josephson tunneling. Similarly, superconductive coherence is also observed in chain and plane layers in YBa₂Cu₃O₆.₈₁. In addition, at the CO phase boundary, the mutually competing behavior between CO and SC phases and a proximity-like boundary region are observed.
The present atomically-resolved XSTM provides a detailed insight into the unexplored interlayer coupling and its spatial interplay with superconductivity and therefore offers a new approach to unravel the fundamental physical mechanisms of superconductivity in cuprates.[1]

[1] Chun-Chih Hsu, Bo-Chao Huang, Michael Schnedler, Ming-Yu Lai, Yuh-Lin Wang, Rafal E. Dunin Borkowski, Chia-Seng Chang, Ting Kuo Lee, Philipp Ebert, and Ya-Ping Chiu, “Atomically-resolved interlayer charge ordering and its interplay with superconductivity in YBa₂Cu₃O₆.₈₁”, Nature Communications, 12, 3893 (2021).

Keywords: STM, Superconductivity, Charge density waves