Source capture
Authors Jian-Jian Miao, Yue Liu, Yue Zhao, Yichen Hua, Changming Yue, Wei-Qiang Chen
arXiv / Publisher https://arxiv.org/abs/2607.04122
PDF https://arxiv.org/pdf/2607.04122
Relevance score 4.914
Primary category cond-mat.supr-con
Published 2026-07-07
Research paradigm Theoretical
Sample form Thin Film

Summary

Combining a correlated multi-orbital quasiparticle model derived from DFT+CDMFT with the T-matrix method, this study treats oxygen vacancy scattering within a semiclassical Boltzmann transport framework and reveals the microscopic origin of the Hall coefficient sign reversal in bilayer nickelate thin films. Multiband compensation alone is insufficient to explain the phenomenon; in-plane oxygen vacancies strongly suppress the transport channel dominated by the dx2-y2 orbital through orbital-selective scattering, driving the Hall coefficient across zero to become positive, whereas apical oxygen vacancies tend to make the Hall coefficient more negative. This pocket-resolved and orbital-selective scattering mechanism demonstrates that oxygen vacancies act not only as electron doping sources but also as active scattering centers whose spatial distribution directly controls the normal-state transport behavior, providing a theoretical framework for a unified understanding of the diverse Hall responses observed experimentally as a function of oxygen stoichiometry.

Materials

Methods

Keywords

Highlights

  • A correlated multi-orbital quasiparticle model with T-matrix treatment of oxygen-vacancy scattering provides a unified microscopic explanation for the Hall coefficient sign reversal.
  • In-plane and inner-apical oxygen vacancies have qualitatively different effects on the Hall coefficient due to orbital-selective scattering, rooted in the distortion of the local crystal-field environment.
  • The study demonstrates that oxygen vacancies act as active scattering centers beyond simple electron doping, with their spatial distribution being a key control parameter for transport properties.
  • The theoretical framework reconciles the seemingly contradictory Hall data across different nickelate films by accounting for oxygen stoichiometry and vacancy distribution.

Conclusions

  • Multiband compensation by itself cannot account for the Hall coefficient sign reversal in bilayer nickelate films.
  • In-plane oxygen vacancies selectively suppress the dx2-y2 orbital transport channel, driving the Hall coefficient from negative to positive, while inner-apical vacancies make it more negative.
  • Orbital-selective oxygen-vacancy scattering, rather than rigid-band electron doping, is the microscopic origin of the sign reversal.
  • The results provide a framework for understanding the diverse Hall responses observed in nickelate films as a function of oxygen stoichiometry.

Main claims

  • Orbital-selective oxygen-vacancy scattering drives the Hall coefficient sign reversal in bilayer nickelate films.
    • Evidence: In-plane vacancies suppress the transport channel dominated by the dx2-y2 orbital, driving R_H positive.,Inner-apical vacancies make R_H more negative and do not produce a sign change.,Mixed distributions with sufficient in-plane vacancy fraction reverse sign.
  • Multiband compensation alone cannot explain the Hall coefficient sign reversal; oxygen-vacancy scattering is necessary to select the competing channels.
    • Evidence: Rigid-band doping calculations show R_H remains negative over the considered range.,Without vacancies, the Hall coefficient is negative and dominated by the β pocket.
  • Oxygen vacancies act as active scattering centers, not merely as electron dopants, and their spatial distribution controls normal-state transport.
    • Evidence: In-plane and apical vacancies produce qualitatively different Hall coefficient trends.,The scattering potential from DFT calculations shows strong orbital contrast due to local crystal-field distortions.

Workflow

  • model_setup — The correlated multi-orbital model captures the low-energy electronic structure and ARPES Fermiology of superconducting nickelate heterostructures.
    • Methods: DFT+CDMFT-derived correlated multi-orbital quasiparticle model
    • Observations: quasiparticle Fermi surface consists of three pockets (α, β, γ) with distinct orbital characters
  • transport_calculation — Multiband compensation is insufficient by itself; oxygen-vacancy scattering selects the transport channels that determine the sign reversal.
    • Methods: T-matrix treatment of oxygen-vacancy scattering; semiclassical Boltzmann transport framework; Ong's geometrical interpretation of weak-field Hall conductivity
    • Observations: rigid-band doping alone does not cause Hall coefficient sign reversal; in-plane vacancies drive the Hall coefficient through zero to positive values; inner-apical vacancies make Hall coefficient more negative
  • mechanism_analysis — Pocket-resolved and orbital-selective oxygen-vacancy scattering is the microscopic origin of the Hall coefficient sign reversal, with in-plane vacancies acting as the controlling scatterers.
    • Methods: pocket-resolved and orbital-selective decomposition of Hall conductivity; comparison of inner-apical and in-plane vacancy scattering potentials from DFT
    • Observations: in-plane vacancies selectively suppress the dx2-y2 orbital contribution; the α pocket (dz2) contribution remains nearly unchanged; the sign reversal is driven by the relative suppression of the β pocket contribution