Fermiology of Sr4V2O6Fe2As2: Quasi-Nested Fe vs Mott-Insulating V Orbitals

TL;DR

This study uses angle-resolved photoemission spectroscopy to explore the electronic structure of Sr4V2O6Fe2As2, revealing quasi-nested Fe Fermi surfaces and Mott-insulating V orbitals, highlighting their roles in superconductivity.

Contribution

It provides the first detailed experimental Fermi surface mapping of Sr4V2O6Fe2As2, showing the importance of quasi-nested Fe Fermi surfaces and the Mott-insulating state of V orbitals for superconductivity.

Findings

Fe 3d bands form quasi-nested Fermi surfaces

V 3d orbitals are in a Mott insulator state

Quasi-nested Fermi surfaces support superconductivity

Abstract

We have performed an angle-resolved photoemission spectroscopy study of a new iron-based superconductor Sr4V2O6Fe2As2. While V 3d orbitals are found to be in a Mott insulator state and show an incoherent peak at ~ 1 eV below the Fermi level, the dispersive Fe 3d bands form several hole- and electron-like Fermi surfaces (FSs), some of which are quasi-nested by the (pi, 0) wave vector. This differs from the local density approximation (LDA) calculations, which predict non-nested FSs for this material. However, LDA+U with a large effective Hubbard energy U on V 3d electrons can reproduce the experimental observation reasonably well. The observed fermiology in superconducting Sr4V2O6Fe2As2 strongly supports that (pi, 0) interband scattering between quasi-nested FSs is indispensable to superconductivity in pnictides.