# Combined effects of pairing fluctuations and a pseudogap in the Cuprate Hall effect

## TL;DR

This paper develops a strong-pairing fluctuation theory incorporating pseudogap effects to explain the temperature-dependent Hall coefficient in cuprate superconductors, predicting no sign change above Tc and aligning with experimental observations.

## Contribution

It introduces a novel theoretical approach that combines pairing fluctuations and pseudogap effects to better understand cuprate transport properties near the transition temperature.

## Key findings

- Pseudogap effects influence both transverse and longitudinal conductivities.
- The Hall coefficient's non-monotonic temperature dependence results from fermionic and bosonic interplay.
- No sign change in Hall coefficient is predicted above the transition temperature.

## Abstract

The normal-state behavior of the temperature-dependent Hall coefficient in cuprate superconductors is investigated using linear response theory. The Hall conductivity is of paramount importance in that its sign and magnitude directly reflect the sign of the charge carriers and the size of particle-hole asymmetry effects. Here we apply a strong-pairing fluctuation theory that incorporates pseudogap effects known to be important in cuprate transport. As a result, in the vicinity of the transition temperature our theoretical approach goes beyond the conventional superconducting fluctuation formalism. In this regime, pseudogap effects are evident in both the transverse and longitudinal conductivities and the bosonic response is explicitly gauge invariant. The presence of a gap in the excitation spectrum is also apparent at higher temperatures, where the gapped fermionic quasiparticles are the dominant contribution to the Hall coefficient. The observed non-monotonic temperature dependence of the Hall coefficient therefore results from a delicate interplay between the fermionic quasiparticles and the bosonic fluctuations. An important feature of our work is that the sign of the Hall conductivity from the Cooper pair fluctuations is the same as that of their fermionic constituents. Thus, we find no sign change in the Hall coefficient above the transition temperature. This prediction is corroborated by experiments, away from special charge ordering stoichiometries. The theoretical results presented in this paper provide crucial signatures that can be experimentally verified, enabling validation of the present theory.