# Multiple electronic components and Lifshitz transitions by oxygen wires formation in layered cuprates and nickelates

## TL;DR

This paper predicts how oxygen wire self-organization in layered cuprates and nickelates creates complex multi-band electronic structures and Lifshitz transitions, potentially influencing high-temperature superconductivity.

## Contribution

It provides the first theoretical prediction of multi-band electronic structures and Lifshitz transitions caused by oxygen wire formation in layered cuprates and nickelates.

## Key findings

- Oxygen interstitial wires induce quantum confined states.
- Formation of Lifshitz transitions in electronic structure.
- Potential link to Majorana states in superconductors.

## Abstract

There is a growing compelling experimental evidence that a quantum complex matter scenario made of multiple electronic components, and competing quantum phases is needed to grab the key physics of high critical temperature (Tc) superconductivity in layered cuprates. While it is known that defects self-organization controls Tc, the mechanism remains an open issue. Here we focus on the theoretical prediction of the multi-band electronic structure and the formation of broken Fermi surfaces generated by the self-organization of oxygen interstitials O-i atomic wires in the spacer layers in HgBa2CuO4+y, La2CuO4+y and La2NiO4+y, by means of self-consistent Linear Muffin-Tin Orbital (LMTO) calculations. The electronic structure of a first phase of ordered O-i atomic wires and of a second glassy phase made of disordered O-i impurities have been studied through supercell calculations. We show the common features of the influence of O-i wires in the electronic structure in three type of materials. The ordering of O-i into wires lead to a separation of the electronic states between the O-i ensemble and the rest of the bulk. The wires formation produce first quantum confined localized states near the wire which coexist with second delocalized states in the Fermi-surface (FS) of doped cuprates. In this new scenario for high Tc superconductivity, Kitaev wires with Majorana bound states are proximity-coupled to a 2D d-wave superconductor in cuprates.