Temperature variation of the pseudogap in underdoped cuprates

TL;DR

This paper investigates how the pseudogap in underdoped cuprates evolves with temperature, revealing a strong coupling behavior where the spectral function exhibits a sqrt(Omega) dependence and identifying the temperature T* where the gap closes.

Contribution

It introduces a strong coupling model for the spectral function in underdoped cuprates, showing the temperature dependence of the pseudogap and the effects of classical fluctuations.

Findings

Spectral function near (0,π) behaves as sqrt(Omega) in strong coupling.

A leading edge gap exists and broadens at higher frequencies.

The pseudogap closes at T* around 200K due to classical fluctuations.

Abstract

We consider thermal evolution of the spectral function A(Omega, T) in underdoped cuprates at T >Tc. We find that in the strong coupling limit, the fermionic Green's function near (0,\pi) behaves as G^{-1} (Omega) ~ \sqrt{Omega} in the whole frequency range relevant to photoemission experiments. The analysis of the pairing problem with this form of G yields a leading edge gap in A(\Omega) and a broad maximum at larger frequencies. We find that classical fluctuations predominantly add a frequency independent term to G^{-1} (Omega). This term destroys the leading edge gap at T =T* (k)$which has a maximum value of about 200K near (0,\pi).