Evolution of electron Fermi surface with doping in cobaltates

TL;DR

This paper investigates how the electron Fermi surface in cobaltates evolves with doping using the t-J model, revealing Fermi-arc phenomena at low doping and adherence to Luttinger's theorem.

Contribution

It provides a theoretical analysis of the doping-dependent evolution of the electron Fermi surface in cobaltates, including the prediction of Fermi-arc phenomena.

Findings

Fermi surface obeys Luttinger's theorem.

Fermi-arc phenomena emerge at low doping.

Fermi arcs weaken with increased doping.

Abstract

The notion of the electron Fermi surface is one of the characteristic concepts in the field of condensed matter physics, and it plays a crucial role in the understanding of the physical properties of doped Mott insulators. Based on the t-J model, we study the nature of the electron Fermi surface in the cobaltates, and qualitatively reproduce the essential feature of the evolution of the electron Fermi surface with doping. It is shown that the underlying hexagonal electron Fermi surface obeys Luttinger's theorem. The theory also predicts a Fermi-arc phenomenon at the low-doped regime, where the region of the hexagonal electron Fermi surface along the \Gamma-K direction is suppressed by the electron self-energy, and then six disconnected Fermi arcs located at the region of the hexagonal electron Fermi surface along the \Gamma-M direction emerge. However, this Fermi-arc phenomenon at the low-doped regime weakens with the increase of doping.