Effects of proximity to an electronic topological transition on normal state transport properties of the high-Tc superconductors

TL;DR

This paper investigates how proximity to an electronic topological transition affects the transport properties of high-Tc superconductors, revealing abrupt changes in fluctuation behavior linked to doping and anisotropy.

Contribution

It provides a theoretical evaluation of the imaginary part of the relaxation rate near an ETT in high-Tc cuprates, connecting it to experimental fluctuation effects and anisotropy.

Findings

Im gamma changes sign at the ETT with doping.

Increased anisotropy enhances fluctuation effects near ETT.

Results qualitatively agree with excess Hall conductivity data.

Abstract

Within the time dependent Ginzburg-Landau theory, the effects of the superconducting fluctuations on the transport properties above the critical temperature are characterized by a non-zero imaginary part of the relaxation rate gamma of the order parameter. Here, we evaluate Im gamma for an anisotropic dispersion relation typical of the high-Tc cuprate superconductors (HTS), characterized by a proximity to an electronic topological transition (ETT). We find that Im gamma abruptly changes sign at the ETT as a function of doping, in agreement with the universal behavior of the HTS. We also find that an increase of the in-plane anisotropy, as is given by a non-zero value of the next-nearest to nearest hopping ratio r=t'/t, increases the value of | Im gamma | close to the ETT, as well as its singular behavior at low temperature, therefore enhancing the effect of superconducting fluctuations. Such a result is in qualitative agreement with the available data for the excess Hall conductivity for several cuprates and cuprate superlattices.