The mid-infrared Hall effect in optimally-doped Bi_2 Sr_2 CaCu_2 O_{8+\delta}

TL;DR

This study measures the mid-infrared Hall effect in optimally doped Bi2Sr2CaCu2O8+δ, revealing simple Drude behavior in Hall conductivity and providing insights into carrier dynamics and interactions in high-temperature superconductors.

Contribution

It presents the first detailed frequency and temperature dependence of the mid-IR Hall effect in this material, highlighting contrasting behaviors of Hall and longitudinal scattering rates.

Findings

Hall scattering rate increases linearly with temperature

Hall frequency suggests a carrier mass 6.7 times the band mass

Hall conductivity exhibits simple Drude behavior

Abstract

Heterodyne polarometry is used to measure the frequency dependence in the mid IR from 900 to 1100 cm$^-1$ and temperature dependence from 35 to 330 K of the normal state Hall transport in single crystal, optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. The results show a simple Drude behavior in the Hall conductivity $\sigma_{xy}$ which stands in contrast to the more complex, extended Drude behavior for the longitudinal conductivity $\sigma_{xx}$. The mid IR Hall scattering rate $\gamma_{xy}$ increases linearly with temperature and has a small, positive, projected intercept at T=0. The longitudinal scatter rate, in contrast, is much larger and exhibits very little temperature dependnece. The Hall frequency indicates a carrier mass which is 6.7 times the band mass and which decreases slighly with increasing frequency. These disparate behaviors are consistent with calculations based on the fluctuation-exchange interaction using current vertex corrections.