Perez-Muñoz, Ana M.Schio, PedroPoloni, RobertaFernández Martínez, AlejandroRivera-Calzada, AlbertoCezar, Julio C.Salas Colera, EduardoCastro, German R.Kinney, JosephLeón, CarlosSantamaria, JacoboGarcia-Barriocanal, JavierGoldman, Allen M.2023-01-172023-01-172017-01-10Perez-Muñoz, A. M., Schio, P., Poloni, R., Fernandez-Martinez, A., Rivera-Calzada, A., Cezar, J. C., Salas-Colera, E., Castro, G. R., Kinney, J., Leon, C., Santamaria, J., Garcia-Barriocanal, J. & Goldman, A. M. (2016). In operando evidence of deoxygenation in ionic liquid gating of YBa2Cu3O7-X. Proceedings of the National Academy of Sciences, 114(2), 215-220.0027-8424https://hdl.handle.net/10016/36287These results underscore the debate on the true nature, electrostatic vs. electrochemical, of the doping of cuprates with ionic liquids. Here, we address the doping mechanism of the high-temperature superconductor YBa2Cu3O7-X (YBCO) by simultaneous ionic liquid gating and X-ray absorption experiments. Pronounced spectral changes are observed at the Cu K-edge concomitant with the superconductor-to-insulator transition, evidencing modification of the Cu coordination resulting from the deoxygenation of the CuO chains, as confirmed by first-principles density functional theory (DFT) simulations. Beyond providing evidence of the importance of chemical doping in electric double-layer (EDL) gating experiments with superconducting cuprates, our work shows that interfacing correlated oxides with ionic liquids enables a delicate control of oxygen content, paving the way to novel electrochemical concepts in future oxide electronics.6eng© The Authors, 2016.Electric double-layer techniquesFirst-principles density functional theoryHigh-temperature superconductivityNear-edge X-Ray absorption spectroscopiesSuperconductor-insulator transitionresearch articleEnergías Renovableshttps://doi.org/10.1073/pnas.1613006114open access2152220Proceedings of the National Academy of Sciences114AR/0000027047