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Critical role of hydrogen for superconductivity in nickelates

DOI: 10.1038/s41586-022-05657-2 DOI Help

Authors: Xiang Ding (University of Electronic Science and Technology of China) , Charles C. Tam (Diamond Light Source; University of Bristol) , Xuelei Sui (Beijing Computational Science Research Center) , Yan Zhao (University of Electronic Science and Technology of China) , Minghui Xu (University of Electronic Science and Technology of China) , Jaewon Choi (Diamond Light Source) , Huaqian Leng (University of Electronic Science and Technology of China) , Ji Zhang (University of New South Wales) , Mei Wu (Peking University) , Haiyan Xiao (University of Electronic Science and Technology of China) , Xiaotao Zu (University of Electronic Science and Technology of China) , Mirian Garcia-Fernandez (Diamond Light Source) , Stefano Agrestini (Diamond Light Source) , Xiaoqiang Wu (Chengdu University) , Qingyuan Wang (Chengdu University) , Peng Gao (Peking University) , Sean Li (University of New South Wales) , Bing Huang (Beijing Computational Science Research Center; Beijing Normal University) , Ke-Jin Zhou (Diamond Light Source) , Liang Qiao (University of Electronic Science and Technology of China)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature , VOL 615 , PAGES 50 - 55

State: Published (Approved)
Published: March 2023
Diamond Proposal Number(s): 30296

Abstract: The newly discovered nickelate superconductors so far only exist in epitaxial thin films synthesized by a topotactic reaction with metal hydrides1. This method changes the nickelates from the perovskite to an infinite-layer structure by deintercalation of apical oxygens1,2,3. Such a chemical reaction may introduce hydrogen (H), influencing the physical properties of the end materials4,5,6,7,8,9. Unfortunately, H is insensitive to most characterization techniques and is difficult to detect because of its light weight. Here, in optimally Sr doped Nd0.8Sr0.2NiO2H epitaxial films, secondary-ion mass spectroscopy shows abundant H existing in the form of Nd0.8Sr0.2NiO2Hx (x ≅ 0.2–0.5). Zero resistivity is found within a very narrow H-doping window of 0.22 ≤ x ≤ 0.28, showing unequivocally the critical role of H in superconductivity. Resonant inelastic X-ray scattering demonstrates the existence of itinerant interstitial s (IIS) orbitals originating from apical oxygen deintercalation. Density functional theory calculations show that electronegative H– occupies the apical oxygen sites annihilating IIS orbitals, reducing the IIS–Ni 3d orbital hybridization. This leads the electronic structure of H-doped Nd0.8Sr0.2NiO2Hx to be more two-dimensional-like, which might be relevant for the observed superconductivity. We highlight that H is an important ingredient for superconductivity in epitaxial infinite-layer nickelates.

Subject Areas: Materials, Physics

Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)

Added On: 06/03/2023 08:55

Discipline Tags:

Surfaces Superconductors Quantum Materials Physics Materials Science interfaces and thin films

Technical Tags:

Scattering Spectroscopy Resonant Inelastic X-ray Scattering (RIXS) X-ray Absorption Spectroscopy (XAS)