Role of topotactic hydrogen in superconductivity of infinite-layer nickelate NdNiO2: A first-principles and variational Monte Carlo study

Abstract

Employing a combination of first-principles calculations, low-energy model construction, and variational Monte Carlo solution of the ab initio derived Hubbard model, we study the effect of hydrogenation on the electronic structure and superconducting properties of an infinite-layer nickelate, NdNiO2. We find that the introduction of hydrogen at the apical oxygen vacancy position strongly influences the Wannier function corresponding to the effective interstitial orbital at the Ni site bound to hydrogen. This results in the near disappearance of the electron pocket at the kz = π Fermi surface, keeping that of kz = 0 unchanged, compared to the dehydrogenated case. The two-band model description thus remains valid even in the presence of H. The calculated superconducting order parameters both in the absence and the presence of H, show orbital-selective superconductivity, one arising from dx2−y2 and another arising from the interstitial orbital degree of freedom. Hydrogenation strengthens the former and weakens the latter in the filling range n≤ 1.

Source-reported materials — not catalogue approval

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