Role of the apical oxygen in cuprate high-temperature superconductors
Abstract
Scanning tunneling microscopy measurements exploiting the natural superstructure modulation of the cuprate superconductor Bi2Sr2CaCu2O8+x (Bi-2212) have revealed a possible correlation between the Cu-apical-O distance δapi and the superconducting order parameter mSC, as reported recently by O'Mahony et al. (Proc. Natl. Acad. Sci. 119, e2207449119 (2022)). These observations were interpreted as evidence for a direct link between superconductivity and the charge-transfer gap, and more broadly revived the long-standing question of the role of apical oxygens in cuprate superconductivity. Using a combination of density-functional theory and cluster dynamical mean-field theory, we compute from first principles the variations of mSC induced solely by apical oxygen displacement in Bi2Sr2CuO6+δ, Bi-2212, and HgBa2CuO4+δ. The quantitative agreement between our calculations and experiments allows us to unambiguously attribute the observed variations of mSC to changes in δapi. We demonstrate, however, that these variations of mSC originate predominantly from changes in the effective hole-doping of the CuO2 planes, with negligible effect on the charge-transfer gap. The modest magnitude of the mSC modulation induced by apical-oxygen displacement alone therefore warrants caution in interpreting correlations between Tc and δapi inferred from comparisons across different cuprate compounds. Our work demonstrates that the present ab initio framework can quantitatively resolve the influence of specific structural degrees of freedom on superconductivity in correlated oxides.
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BibTeX
@article{vadnais2026role,
title = {{Role of the apical oxygen in cuprate high-temperature superconductors}},
author = {Samuel Vadnais and Rémi Duchesne and Kristjan Haule and A. -M. S. Tremblay and David Sénéchal and Benjamin Bacq-Labreuil},
journal = {Physical Review Letters},
year = {2026},
month = sep,
doi = {10.1103/d9cc-jnst},
eprint = {2601.16017},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05489311v2},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - JOUR
TI - Role of the apical oxygen in cuprate high-temperature superconductors
AU - Samuel Vadnais
AU - Rémi Duchesne
AU - Kristjan Haule
AU - A. -M. S. Tremblay
AU - David Sénéchal
AU - Benjamin Bacq-Labreuil
PY - 2026
DA - 2026/09/29
JO - Physical Review Letters
DO - 10.1103/d9cc-jnst
UR - https://hal.science/hal-05489311v2
AB - Scanning tunneling microscopy measurements exploiting the natural superstructure modulation of the cuprate superconductor Bi_2Sr_2CaCu_2O_8+x (Bi-2212) have revealed a possible correlation between the Cu-apical-O distance δ_api and the superconducting order parameter m_SC, as reported recently by O'Mahony et al. (Proc. Natl. Acad. Sci. 119, e2207449119 (2022)). These observations were interpreted as evidence for a direct link between superconductivity and the charge-transfer gap, and more broadly revived the long-standing question of the role of apical oxygens in cuprate superconductivity. Using a combination of density-functional theory and cluster dynamical mean-field theory, we compute from first principles the variations of m_SC induced solely by apical oxygen displacement in Bi_2Sr_2CuO_6+δ, Bi-2212, and HgBa_2CuO_4+δ. The quantitative agreement between our calculations and experiments allows us to unambiguously attribute the observed variations of m_SC to changes in δ_api. We demonstrate, however, that these variations of m_SC originate predominantly from changes in the effective hole-doping of the CuO_2 planes, with negligible effect on the charge-transfer gap. The modest magnitude of the m_SC modulation induced by apical-oxygen displacement alone therefore warrants caution in interpreting correlations between T_c and δ_api inferred from comparisons across different cuprate compounds. Our work demonstrates that the present ab initio framework can quantitatively resolve the influence of specific structural degrees of freedom on superconductivity in correlated oxides.
SN - 0031-9007
SN - 1079-7114
ER -