Lifshitz transition driven by spin fluctuations and spin-orbit renormalization in NaOsO$_3$

TL;DR

This paper demonstrates that in NaOsO₃, a Lifshitz transition driven by spin fluctuations and spin-orbit coupling causes a continuous metal-insulator transition, highlighting a mechanism distinct from traditional Mott or Slater models.

Contribution

It reveals a novel spin-driven Lifshitz transition mechanism in 5d perovskites with small correlations and large hybridization, emphasizing the role of spin-orbit effects.

Findings

Lifshitz transition induces metal-insulator change in NaOsO₃

Spin fluctuations and spin-orbit coupling are key drivers

Weak electronic correlations facilitate the transition

Abstract

In systems where electrons form both dispersive bands and small local spins, we show that changes of the spin configuration can tune the bands through a Lifshitz transition, resulting in a continuous metal-insulator transition associated with a progressive change of the Fermi surface topology. In contrast to a Mott-Hubbard and Slater pictures, this spin-driven Lifshitz transition appears in systems with small electron-electron correlation and large hybridization. We show that this situation is realized in 5$d$ distorted perovskites with an half-filled $t_{2g}$ bands such as NaOsO$_3$, where the strong $p-d$ hybridization reduces the local moment, and spin-orbit coupling causes a large renormalization of the electronic mobility. This weakens the role of electronic correlations and drives the system towards an itinerant magnetic regime which enables spin-fluctuations.