Lifshitz transition in two-dimensional spin-density wave models

TL;DR

This paper investigates Lifshitz transitions in two-dimensional spin-density wave models relevant to underdoped cuprates, analyzing impurity effects and their impact on electrical properties near the transition.

Contribution

It demonstrates how both pocket-disappearing and neck-disrupting Lifshitz transitions can occur in these models and explores their signatures in thermopower and conductivity.

Findings

Thermopower is strongly enhanced near the transition.

Distinct signatures in thermopower differentiate the two transition types.

Impurity scattering effects are incorporated using the self-consistent Born approximation.

Abstract

We argue that both pocket-disappearing and neck-disrupting types of Lifshitz transitions can be realized in two-dimensional spin-density wave models for underdoped cuprates, and study both types of transitions with impurity scattering treated in the self-consistent Born approximation. We first solve for the electron self-energy from the self-consistent equation, and then study the low-temperature electrical conductivity and thermopower. Close to the Lifshitz transition, the thermopower is strongly enhanced. For the pocket-disappearing type, it has a sharp peak, while for the neck-disrupting type, it changes sign at the transition, with its absolute value peaked on both sides of the transition. We discuss possible applications to underdoped cuprates.